Modern cars are ridiculously overpowered. Every year, the new models need to be better than the old models and better than the competition.

Farm equipment just needs to get the job done. A tractor rarely needs to work at more than 5 mph. So no reason to spend money on a larger engine.

Most commercial equipment has a lot less hp than you'd expect. When whoever is buying equipment is looking at operating costs, purchase price, expected profit, they buy just what they need, not what is most fun.

Most consumers on the other hand think, I may tow a trailer in the mountains one day, so I'd better get the bigger engine just in case. Commercial operators say put it in 2nd gear and go slow.