If several people in a similar location want burgers from the same restaurant at the same time? Great. On the other hand, if they're in different parts of town

If several people in a similar location want burgers from the same restaurant at the same time? Great. On the other hand, if they're in different parts of town? Can't carpool. If they order 30 minutes apart? Unless your service is slow as hell, can't carpool. If they order from different restaurants? One customer's food is going to be sitting around, maybe getting cold, while the driver stands around waiting to be served at the second restaurant. If that's not acceptable, can't carpool. If the customer density is high enough these things work out OK - but a lot of these services operate in areas where the customer density doesn't look high enough.