[bobitsaboy]

Unless it's completely dead, every pizza shop runs multiple orders at once and their drivers are in and out swiftly. The food stays fairly hot thanks to commercial heat bags.

For the delivery apps, the driver has to possibly wait in a line, check it out, then deliver the order a single order at a time.

[TylerE]

Many of the apps will actually batch multiple orders from the same restaurant to multiple near(ish) dropoffs.

[jen20]

Presumably this is the reason the food delivered by all these services is cold whenever it arrives.