Animal cruelty? Better become a vegetarian, since they keep 5-10 chickens in 2x2ft cages.
Retics should have cages a bit bigger than burm, that I agree with.
However, we have a 15ft burm at the zoo in a cage 20ft long and 6ft wide. I don't think I've ever seen her move out of the same 5x5ft corner by her water. It's the biggest waste of space I've ever seen.
Burms would be ok in a 6-7ftx3-4ft cage until 18ft. Retics I think should be in 8-9ft cages since they are more active.