Ponies and compact engines?

Kinda missed it back then. Bow Hothoof have this. This is some sort of lawn mower for clouds. But funny thing - considering sound it makes and exhaust pipe it obviously has an engine. I don't know what sorts of engine it uses - some ultra-compact steam engine or maybe internal combustion one. It's really don't matter. Point is - ponies can do something like this and it's obviously affordable at least for middle-class. And then a really big question - why the hell they don't have cars? Yes, Doylist answer that shows creators randomly insert different pieces of technology just for the lulz. But what about Watsonian explanations?
I'm myself only able to come with one explanation - that Equestria in middle of some fast progress phase and so they invent things faster than they know what to do with them.