Comment by bombcar

It's about usable time and cost of capital - if it's cheaper to rent the unit, they'll rent one, if it's cheaper to buy one and let it sit idle most of the time, they'll do that.

The rent/buy calculus can be incredibly shunted towards "buy" once you're using it even somewhat. It's even more so when you realize that labor costs is the main issue, and not having a skilled worker waiting around for an item to be delivered (by another slightly less skilled worker, perhaps) is a huge savings in its own part. Five guys on a site might have 15 machines total; even though they obviously can't use all 15 at the same time.