[lentil]

> many payroll softwares will test decently

That's certainly the impression I got from working in this field for a while. I've worked on one of the products on that list of UK payroll providers, and it has one of the most extensive test suites that I've seen. And some of my colleagues there had previously worked for its competitors, and they mentioned similarly good test coverage there.

I'm sure the quality & amount of testing varies a lot between different products, and I have to imagine there are some dreadful ones. But at the same time, I don't think having thorough test coverage for this type of product -- especially for the parts of the product that deal with monetary calculations -- is particularly unusual either.