I guess I have a naive view. I think of "buy" as something which is a capital expenditure, can be depreciated, etc. while "rent" are things which fall under operational expenditure.

With that in mind, I can see support contracts as an operational expenditure.

But if "over half of industrial robot purchases in North America have been made by automakers" then that's a lot of capital expenditure. I never got the feel that the companies which make modern industrial robots primarily rented them out (akin to IBM's renting out of tabulation machines 100 years ago). I really thought they mostly sold the robots.