In most places, restaurants aren't allowed to give them free food. (edit: as a commenter pointed out, may be more of a police policy than a legal one) Yet you'll always see restaurants frequented by cops on-duty - guess which ones are breaking those rules.
Right, I know there are laws preventing law enforcement from accepting gifts. I was skeptical that there are laws preventing businesses from offering them.
Honestly no, other than conversations I've had in various places with people who ran some eating establishments. It may be more of a police department policy, as the other commenter mentioned.
In most places the onus is on the police not to accept free food. It is their professional duty not to take free items. Because it starts to smell a bit like a protection racket, even if originally people offered out of true generosity/thankfulness.
It's a enormous stretch to call it bribery. Amazon isn't asking the police to look the other way. They aren't encouraging anything unethical or a breach of trust. Any more than a free laundry soap sampler in the mail is bribery.
Should the police have regulations about this sort of gift? Should, they probably do, and those that don't should.