How do you know this? It frankly doesn't sound like you have worked on an application of similar scope that has good test coverage. I went the first decade of my career without writing tests and said the exact same things you are saying.
I do agree that learning how to write effective tests is difficult and that you cannot do it by reading the web tutorials and the scant coverage given in most books. I learned how by working on an existing project with good coverage.
On my own personal projects what I began doing was writing tests instead of writing most of the exploratory code in the REPL, or instead of writing a stub of a template to test some new code in the browser. I took all that ad-hoc scaffolding that naturally pops up and just structured a little bit and called that my tests. My tests are more integration tests ... I still do not understand the compulsion for low-level unit tests that do nothing other than prove the underlying framework works correctly.
