I don't know what they are using in the factory, but I will at least weigh in with my experience. The paint on my 2006 zero turn ROPES came off in sheets, no adherence. I took it off, sanded it and repainted it with Kubota aerosol paint with good success. I am not sure what caused the lack of adhesion, but the aerosol seems to be working on parts with little abuse.
On my 78-81 tiller, snow blower, FEL and dozer blade sub-frame, I had the paint all removed by sand blasting and then professionally powder coated. I did them all at one time, so the price wasn't terrible. The total was around $500 and the powder coat is really tough. In my opinion, anything that has a lot of rough duty, like snow blowers and tillers, powder coating is the way I plan to go. At least scratches down to bare metal don't rust as bad. It seems like the powder coat impregnates the metal better than paint.
John