And how would tracing me with a bill work? I go to the store, buy something, get a bill that says date, time, name of the article and price, that's it.
How does that point towards me?
Maybe he was referring to the payment being done online, when the whole thing involved shipping, and buyer need to give his home address/name for delivery. If you pay this way, tax office can always ask store to provide them with all the information they require, and so can identify anyone who pays with crypto.
Paying with crypto directly in store without any ID or KYC it will certainly not cause any investigation, especially for small amounts. However, it should be emphasized that most of those who accept crypto do it through payment processors, and that the conversion takes place right there, the buyer pays in crypto and the seller gets fiat. However, it all depends on the total amount and capacity of the tax administration to investigate such cases.