In a lot of cases, the landlord pays for a management service. That services job is to keep rent flowing and expenses down.
That said, cheap repairs make financial sense. Most will be good enough to not cost a ton later, and the few that aren’t… well, they usually take a while before they end up costing a lot. So the money is in the hands of the landlord longer, and they can invest it in more properties… so they get all the savings from the cheaper repairs, plus the investment income of that savings. From that they can pay for the things that go horribly wrong. Most of the time it will work out in their advantage. And of course they can always sell the house before the expensive repairs to someone who will do those repairs themselves and flip the house. That is the problem with money based decisions.