I indeed see people calling pretty much any tests, except e2e test unit-tests. However as per which test types to use: the right answer is (as with everything)

I indeed see people calling pretty much any tests, except e2e test unit-tests. However as per which test types to use: the right answer is (as with everything) "it depends". When doing testing the overarching problem is that the testing was well thought. Different types of testing will behave differently at different scales and different problems. Instead developers oftentimes thing in terms of WHAT, not WHY. One can't just do the same thing for completely different projects and expect the same results. Most of the time best testing is opportunistic - one that does what's easy and fast to achieve. In some apps functional test will test mostly separate and shallow code paths, which will not lead to a lot of coupling. With some languages a good type-system is already a 90% of unit test suite. A big part of testing is also designing your production code to be testable. (TDD is good here because it forces you to think about it upfront). With a right architecture even e2e test can be great.