Why? An animal is an animal. What difference does it make if you buy it or catch it in the wild?

True but the animals in question were bred as pets and as such there are laws against that states vary but it is illegal.

Some people did that here, they said we eat that in our country, and were charged.

Pending the part of the country you reside, turtle has it's own season. Rattlesnake on the other hand may not be as regulated. All turtle are not good to eat. The common Box turtle found in the US is not of an eating variety. That would be the same kind one would find in pet stores. Softshell, Loggerhead and Snapper are the kind sought after for consumption.

Still, I'd imagine some sort of federal law is in play as far as certain pets are concerned.

Yup! I spent a month in Peru and had it, Guinea pig tastes amazing. Very dark meat. They're large down there though, they actually have a good amount of mass on them, not like the little guys you buy in the US for pets.

Ah, alright. Legal regulations aren't surprising.