With most testing and verification, there's a law of diminishing returns. It helps you find stuff that you need to fix and there is always stuff to find. But at some point you've found enough of the stuff that needed fixing that you can use the software and it starts making money for you. Most people stop there. It's not going to make much more money if you continue your efforts and the risk of a lot of financial damage is usually not that high. A good software license will ensure that. You might be better off paying a decent lawyer than wasting time on formal methods. Lawyers aren't cheap. But neither is having your software engineering team faff about with a lot of complex tools for weeks on end.

And with software you can just do an update if something is found later. Not a big deal usually. There are exceptions of course. With hardware things get more expensive. But still, judging from the state of e.g. most bluetooth and other hardware I've ever owned, the barrier of good enough is pretty low there too. Mostly things work and you can usually work around minor issues when they don't.

Some, software justifies/requires going above and beyond doing testing. Especially if it controls critical hardware. I've never worked on such stuff. And even there the notion of releasing often and breaking stuff by testing it seems to be catching on. For example SpaceX is doing agile rocket development. They launch starship every few months until they get it reliable enough to launch things into orbit.

I doubt that although I agree that it's much more useful when cost of a failure is higher. For example I work in a lab that formalizes requirements and we have real customers that pay us for formalization because they find it useful. Some products are things that a failure could cause injury or even possibly death. But not all systems have that high costs and they still see benefits.