It's true that drivers don't earn much in the end when it comes to $ / year—but the "truck" does cost quite a bit: fuel, maintenance, insurance, equipment loans, etc.

The driver is still making ~50% of the overall cost of a truck (whether that amounts to a livable wage is a whole 'nother discussion).

https://www.freightwaves.com/news/understanding-total-operat... has a good breakdown of the cost structure for carriers.