But my logic is correct. If he had just spent it on food he didn't need, he would be in the clear. So then the conclusion must be the policy doesn't work.

The policy is very relevant, in fact it's the only relevant piece of information. You want to prevent stealing? Don't offer your employees stipends. Problem solved, I'll send everyone my invoice.

This is a simple case of having their cake and eating it too. You cannot simultaneously be "generous" and be stingy. Meta intends to keep a certain image, while they maintain actions that contradict that image.

> The company trusts employees to use benefits with responsibility

Correct, the company is being incredibly stupid and naive. They maintain a purely transactional relationship with their employees, and it's in their own best interest to keep that kind of relationship. Such a relationship is not, and will never be, one of "trust" or "morals". The company seemingly forgot what they are.