Why is there a age limit at all.All you doing is delivering food.
True. Other delivery companies (DoorDash and Postmates for sure, probably Grubhub too) don't set vehicle age requirements for delivery. All they require is that your car is legal to drive where you work.
For example:
UberX in my area requires a 2002 model 4dr sedan or newer with seat belts for 5. (including driver) on a blue title, no salvage or rebuilt vehicle titles.
UberEATS in my area requires a 1997 model vehicle, 2 or 4 doors OK, and salvage/rebuilt is OK. This, however requires an UberEATS only account at 35% commission. If you have a "rideshare" account that also can do UberX, your car must meet UberX requirements to do delivery as well.. but you get the lower commission rate. (I found all this out the hard way trying to add a 1998 model year minivan to my account for delivery use only.)
DoorDash requires that you enter your vehicle information in the profile, and you have to speak with support if you want switchable vehicle profiles instead of logging in to your profile to change your vehicle info every time you drive a different vehicle for delivery. There doesn't seem to be any verification, though - I suspect the info is just passed on to the customer so they can identify you upon arrival.
Postmates doesn't require any vehicle information..just set your general vehicle type (bicycle, motorcycle, scooter, car, truck, van, etc.) and go right ahead.