the weird issue for mcdonalds is that their margins on food are terrible. they make a large portion of their money selling drinks. I know this because everyone in my family except for me does that math for a living, for other fast food chains.

so in a weird way, they don't really want you to order a lot of food: they want you to order a little bit of food, order a drink, and then get out of the way for the next person. in low-throughput places, ordering more food is fine, because they do still make a little bit of money (unless it's cheap stuff where they lose money). but in high-throughput places, like city centers, they want a bunch of customers, each ordering a drink and as little else as possible.