It's what the UK does too - I never had to file anything for taxes if I only had reported salaried income. Even stuff like interest or investments is mostly automatically handled, you often need to be doing something a little unusual in that area to require anything.

And even if you did have some side income to report, the HMRC website had most things in a pretty easy wizard-like form, similar to turbotax or the like, with the things they already knew about pre-filled.