Really? I was just looking a Michelin starred restaurant and their tasting menu was 300 euros. I suppose you could pay with three different bills, but it's nice to be able to just carry one as well as smaller bills. An a flagship phone is a lot more, so if you want to buy it in cash, that's another very normal transaction that would a require a large stack that's not able to fit in a wallet.
It's soon to be illegal in most of Europe anyway. Cash payments are capped nearly everywhere nowadays with varying limits (sometimes you can do it but have to fill in a declaration above a certain amount) and there is a draft regulation in the EU which would cap them to 7000€ everywhere if the sender can't be identified.