[astrange]

Anyone who works for a FAANG couldn't have their taxes done automatically - the IRS doesn't know the cost basis of your share compensation. Same for anyone with crypto trades, or more prosaically anyone who's sold anything at a flea market or garage sale.

Conversely if you buy and sell the same stock with two different brokers and cause wash sales, or do anything with HSA investments in California, TurboTax and any other consumer tax product will not get your taxes right, and it may not even be possible to do them properly by hand, so everyone is doing them wrong and the IRS just isn't noticing.

Good thing ignorance is a defense for taxes.