There is a lot of evidence from other countries too. In Australia, the Government provides a free web app (used to be a Windows/Mac app) where you can file your taxes. 90% of people can just check that the income figures reported by employers are right, maybe throw in some deductions and click 'file'. You get a refund transferred and a receipt (or bill) by email within the next two weeks.

It basically does everything that an individual could need to do, although you can go to an accountant if you want (if you can't be bothered, or have particularly complex things you need advice on).