Or at least a meal from the restaurant.
Another point is that in most countries outside of the US, panhandlers are either "working for themselves" and make decent money, perhaps better than at a low-end job while having proper living arrangements, etc (and thus "rob" the true poor from the donation). It can also be worse, with situations where panhandlers are actually curated by an organizer who pays them a salary and takes a profit. The latter schemes are also mixed up in exploitation.
Now that I type it all out, I am realizing that buying a meal also prevents the second scenario too. Good stuff.
You buy a McD combo drop it off and feel good. They have to eat it right away. There stomach will not be able to handle it all. They cannot save split the food.
If you give them money they could still dumpster dive for food, keep the money and buy other things they need like (maxi pads, or 1 food bar every morning for a week or a stamp to mail someone or quarters to make a call). They can buy a smaller meal or food in a form that will allow them to space it out over time. Most importantly they can buy the type of food that works best from them.
5 dollars could have multiplier effect. A pre-purchased fast food meal will leaving the homeless person craving for days.
The homeless are drinking/doing drugs less than homed people drinking/doing drugs because they don't have the resources. I would be concerned with salaried beggers.