The reason you get your alignment checked on a new coach is because it's initially done when the coach is empty. I'm guessing on some of the gas chassis, it might even be done before they put the body on.
Yes, there are many that get by with never having an alignment done. The problem is.....if the alignment is out, it's then to late to save the tires. On a car, you can move them to the rear, on most motor homes (without a tag) you're stuck with leaving them in the front position. Once a tire starts to wear from alignment issues, even if the alignment is corrected, the edges that have worn, now scuff instead of riding on the road surface. Scuffing wears down tires faster than driving on them. So the wear pattern is accelerated. At the price of these tires, some common sense care pays for itself.