Because they're tiny and can't carry much. There's a world of difference between a pickup and a truck. It's difficult to buy them with 8' beds, most have 6-6.5'

Because they're tiny and can't carry much. There's a world of difference between a pickup and a truck. It's difficult to buy them with 8' beds, most have 6-6.5' bed which makes carrying construction materials more difficult/dangerous. They have small load limits, which probably is for the best because you rarely can bring down the sidewalls to forklift decently sized stuff anyway! They have their niche, but that's what they are, niche tools that got heavily pushed/marketed to everyone when a car/van or actual truck would be so much better of a fit for their needs.