At my job, I load full pallets of concrete, drywall, plywood, etc, into customer trucks all day every day.
The bigger the truck, the more likely the customer is going to be a pain in the ass. Wishy washy about how much load they can carry, and crying up a storm if you touch the tailgate.
Smaller truck? Load up and go, They'll probably be back for more in a few hours too.
I like to tell people that if their truck can't handle the load, then they paid too much for the truck.
Also also, bigger trucks tend to be parked like douchbaggs more often than smaller trucks, just blocking the way for everyone.