You're right, I looked it up. SaaS software is essentially rented but that's not the same thing as "rent seeking" by the company. I think that's an unfortunate name for the bahavior. The examples I found sound like getting a legislated flow of money for doing nothing. In that light, lobbying for tax reductions would be rent seeking? A penny saved is a penny earned - for nothing.
You're talking as though tax is a right of some sort. You shouldn't have to justify keeping your money. Government should justify why it needs to take it, or it's even less different to the mafia knocking on your door.
> I think that's an unfortunate name for the bahavior.
It made sense when it was coined; it's not like that was the day before yesterday. (Can't recall for sure, but I'm guessing Adam Smith, in The Wealth of Nations.)