[jiofih]

A variety of pedestrian reasons:

- they don’t have the appropriate packaging, ie don’t actually do delivery

- it’s inconvenient for their order pipeline / system

- they can’t vouch for the carrier handling, is the food going to arrive still hot? A shaken mess?

- is the carrier going to add or remove something before it reaches the customer?

Any of those can be damaging for the restaurant, losing a customer, or even downright dangerous in the case of incorrect handling.