Why is it illegal to have a sea turtle as a pet?

its illegal to sell them if they are under four inches in america. most likely since it takes important care and if you sell them like this, turtle breeders will be noticed for a felony. It is not a crime to buy them though.

edit: that answer is sorta wrong you cant sell a turtle under 4 inches but its not because important care its because smaller turtles can fit in kids mouth and give them salmonellae