I've been in business for 42 years now. In all that time I have never seen more than 1000 Euros cash in any kind of business transaction, and I have never been offered to be paid in cash. It's always bank transfers on invoice. I've never bought a vehicle cash, I can't even begin to understand why or how someone would want to buy real estate cash. Besides the obvious risks of being robbed the whole idea of keeping that much money or more around in physical form feels strange to me.
Even in the 1980s when I would buy a vehicle it would be through a bank transfer. The only people that sometimes insist they want to do some transaction in cash are usually marketplace sellers that I suspect are professional sellers that are keeping their income out of sight of the taxman and restaurants where the POS machine 'just broke' that are doing the same. And when I say I do not have any cash and it's ok they can send me an invoice or give me their bank account number suddenly their machine starts working again. Ditto with cab drivers.
Just because there isn't more than 1000 Euros cash in people's hands is simply an indictment of the Euro as a currency and the culture around it.