Server wide consensus no one is getting thralls from cages.
So if no one is getting thralls.
How did I obtain one right off of spawn ?
In official public PvP server ?
do you really wanna go back and forth when I clearly was a fresh spawn and found one right off The coast.
It depends on your server.
The amount of people farming jailors
Restart timers. Etc.
The comeback timer would have to be at restart or farming other cages until restart. And then beginning the cycle again. To see who has been captured this time. It’s a great mechanic.
I’m glad it’s working for you, but could it be that you’re not playing the Steam Enhanced Edition?
Looks like we are going to doesn’t it.
Your experience does not match the majority of players. Are you going to say 12-16 players are wrong just because you found an occupied cage after a restart?
“But if I was to judge the rest by how dependable the one at bonebreakers is, the rest are broken”.
That one works right, that is what I mean by dependable. There may be a few others, but the over whelming majority seem to; if they ever had an occupant after a restart, never reapawn another.
Once again if it worked proper you could actually do what you seem to think people are doing, camp cages. But no one is camping cages. Because they are empty.
I never said I waited for a restart.
I found a new public server
Created a character and went to grab that thrall.
Smashed a few rocks on the way and boom.
Easy as pie. 
if you require any assistance
Feel free to lmk the server
Although I must warn you the price will be HIGH.
If you’re interested in my offer lmk, I will send the terms.
Otherwise good luck exile, may The cages be filled with many thralls.
If it helps, I’d be happy to serve as an eye witness if somebody messages me an ID for one the supposedly affected servers, and promise not to poison that offer with threats of ganking. 
And as I’m a complete noob in CE PvP, that promise is even backed by a complete inability to do so!
UPDATE
Went back into the OFFICIAL SERVER
and the THRALL CAGE HAS A THRALL INSIDE
the same location in my video
So it’s gotta be after restart or something
You do get it’s just you right?
I 9 dentist say use this toothpaste and one says not to guess what tooth paste I’m using?
You god like luke with the cages doesn’t in any way convince any one they are not bugged.
It’s a bug, why are you so desperate to prove it isn’t? I’ve had an entire server say there is no people in the cages. Multiple people have posted here to back up my observation. YOU are the only person arguing otherwise. So I’m just going to assume you are here to push my buttons and troll, so hey, you have the day you deserve, K?
Im not trying to troll.
Just explaining that the cages are working
Maybe your server is bugged but the mechanic is working fine.
If you wanna post The public server for someone to hop on if they are interested in doing so. Feel free to post The server with the issue.
Otherwise the cages work fine.
Just thought I’d throw it in, I also play Officials and like expected the cages sometimes have thralls in them. Sometimes they don’t but this can be because someone beat me to ot or it hasn’t spawned yet.
I can only speak for officials but near 100% spots at server reset are the following 4cfrom my experience
Stargazers
Desertwatch
Scuppers Shelter
Spotters squat
All the others tend to be more randomized but those 4 consistently house a thrall at server refresh.
Also please note that I am a lowly legacy user and not privy to if this changed at all for the enhanced version
Do you get it now?
I don’t play on official servers, but rather on private servers that use almost 99% default settings and have no mods. These servers are quite populated and, at least in my experience, everything works as expected: sometimes I find slaves, other times I don’t. But the system definitely works, and I clearly notice that I find more of them when there are fewer people online.
Thrall cages work perfectly fine, as intended. The fact that not every player will find thralls in them is also intended, which is why they’re not set to a 100% fill rate.
The mechanic quoted in the OP is mostly true and you can see it on that page as well, the rate is set to 50%.
What you need to understand is that this 50% is not per cage.. it’s world-wide so EL + Siptah in this case.
At any point in time the server is attempting to have half the cages in the world filled - this does not mean that they’re in the half YOU play in.. If nobody rescues any thralls from cages where they did spawn, the cage you keep checking will not magically spawn a thrall in it even if you wait all day. This doesn’t mean it’s “broken”, it simply means there are enough cages with thralls somewhere in the world that there’s no need to spawn a thrall in that one.
On single player people will find them more often simply because the only cages in existence in the world are the ones they happen to be at, so those will either have a thrall in it or not, if you have 2 cages in a camp one is guaranteed to have a thrall, but even if it’s just one, it’s guaranteed to be rolled when you ge there.
On the server I play on Stargazers virtually never spawns a thrall. My friends have a base near there to farm thralls / starmetal so they are by that cage often and they have never once seen a thrall in that cage. On the other hand over by Narrowneck Span that cage has has a thrall 100%.
However, no one has built near this location and I wondered if the proximity of player builds had an effect on the spawn rates mentioned by @Xevyr below. I really do not know though.
This has been my experience, quit a few cages just never spawn people, some like the one I pointed out, are quite dependable about it. In my book, that is a broken system. I haven’t hunted the map for other cages to see how well they work. Now if we had a beta server I’d put effort in to studying the question. But I’m not testing on live. I’m just noting to 3 or 4 that are on my usual gathering routs.
I somewhat suspect that there some kind of unusual human behavior involved - either somebody intensely, but secretly farming thrall cages, or somebody using some kind of creative strategy to empty them.
Even if you visited 10 cages instead of just 4, a quick probability estimate (done in a rush) shows that the presence of another 5 players in the same region, passing through those same places, would already be enough to reduce your chances of encounter by more than 40%.
You angered Crom and now you’re cursed. 
Jokes aside, can you let me know on that server you’ve experienced this? Will ask the team to do a check and make sure everything is working as it should.
If, IF those cages actually respawned people.
If all the cages worked like the one at bone breakers bend, I’d never have started this thread.