I think the point is that the vast majority of people don't really have a unique tax situation. And all the data already exists. There's just no framework set up to allow this to be automated like there is in other countries.

It should be the case that all your basic taxes get calculated for you and taken at the point you're paid by your employer. Anything exceptional should be able to be claimed back via a web portal somewhere.

So it's not like 160m tax returns NEED to be filed. That's just how it is today.