I'm pretty confident I'm correctly picking up on sarcasm here. But if I understand correctly, that corner case isn't even "real". Suppose you were a drug deale

I'm pretty confident I'm correctly picking up on sarcasm here. But if I understand correctly, that corner case isn't even "real". Suppose you were a drug dealer in a country that automatically handles tax, and most citizens don't need to file a return, e.g. the UK. I'm pretty confident you can still be prosecuted for failure to report the income from your drug dealing, just as you could be for not reporting any other income where the tax wasn't removed from the paycheck.