The system can be complicated, but all those complications can be handled by the tax agency. For the vast majority of people out there, all the data that you put into your tax return is something that IRS already has, or can easily obtain. And when that is not the case, you should really only need to tell them once (and then update if it ever changes, like the number of kids you have).

Tax filing in US is a huge waste of people's time. I wonder if anyone ever computed the amount of people-hours spent on this malarky, and how much productive output it could generate if used for something else.