As a lifetime student of cats, I am sure that attempting to eat food despite human notions of ownership definitely does not require training.
My model of cat thinking would say something like this:
* only some food is worth eating
* some food is guarded by others. assess risk of taking guarded food
* guards can be tested by gradual approach / encroachment
* some guards can be charmed by sympathetic behavior
* some humans refuse food but don’t actually punish, or may get lazy or unwatchful
* some cats can be intimidated into letting you eat first
Someone else’s cat once stole a steak off an outdoor grill and dragged it away into the neighbor’s yard.