If you don't file your tax return, the government will calculate it for you, send you a bill and a document showing how they got there, as well as a list of all the forms they have, and then you either agree with them and pay, or contest it by filing your return.

If all your income is from a job or investments that have a 1099 and you only take the standard deduction, the government already knows exactly what you owe. The only thing they don't know is business income/loss and donations.

For most taxpayers the government could calculate your tax bill without any involvement from you.