A best effort calculation done with partial information is a type of estimate. I agree, this won't work for a big class of people. It won't work for me. But it

A best effort calculation done with partial information is a type of estimate. I agree, this won't work for a big class of people. It won't work for me. But it will work for the majority of tax filers who don't have a 1099 and who don't file a schedule A, B, C, D ... My tax return last year was a half inch thick, printed out. I had to file on paper. I very much understand that this doesn't work for everyone. But it works for most people.