There's also the likely chance your business doesn't have good documentation on how features should work, there are no tests and the thing you're testing is fai

There's also the likely chance your business doesn't have good documentation on how features should work, there are no tests and the thing you're testing is fairly custom tailored to your business that you need to have someone with knowledge of the product and history of it to tell you "oh yes that's supposed to happen that way". Sure if there is a law written down or past written regulations your business follows, that's easy. You've got docs.