For the majority of Americans, they know… Most Americans don’t have passive income streams or investment income. Most Americans, for a given year, don’t have a change in living scenario (marriage, kids, etc). The majority of tax filers take the standard deduction.

Not always. I used taxAct last year to file, as I always do. I paid what I was told I owe by the software. I just received a tax refund in the mail. Just a check with a memo reading "tax refund", no explanation.

Further, that would be true anywhere, since no system is immune to tax fraud or improper communication.

There are lots of warnings before you get audited. You usually get several letters and then are told "preserve your documents, we may be coming." Then they send you an email or give you a phone call. Then, if you don't respond, they show up irate at your door.