[pandaman]

Unlike SUVs, pickups don't have an adjustable suspension (pneumatic or hydraulic springs) so if you had a low bed on an empty pickup, it would have likely compressed the shocks completely under a heavy load, or, alternatively, you'd had shocks so stiff that they would not move without load at all. Most people who carry heavy loads in their trucks prefer neither and opt for the "lifted" look due to the long shocks, which work both empty and loaded.

[amluto]

I wonder why. You can buy adjustable-height suspensions for pickups, but they don’t seem to be factory options. This feature exists for plenty of passenger vehicles.

Surely some truck maker could make, and charge more for, a pickup truck with a low bed, excellent handling at any load condition, and the ability to carry increase ground clearance as needed for off-road use.

A bit of searching suggests that the Dodge Ram, the Rivian R1T, and, hypothetically, the Tesla Cybertruck have adjustable suspensions.

[pandaman]

A passenger car is usually under 6000 pounds itself and rarely has more than a couple hundred pounds payload. A truck like Sierra 2500 that I most often see lifted, is over 10000 pounds with the payload. A reliable air suspension for that kind of weight is likely too expensive to get any customer demand on a work vehicle and unreliable one is to expensive for the warranty. That would be my guess.