The point isn't that nothing costs €3k, but that regular working people rarely have €3k physical cash on hand. Money goes into their bank accounts via direct deposit and they spend it digitally.
In my opinion it's not unthinkable that an older person, someone without a bank account, or someone who works odd-jobs, might save cash in a drawer (regardless of whether that's advisable) for a long time for a larger purchase, like a used car bought in-person directly from someone else. Should we ban that?
Is it possible to have no bank account in the Netherlands? Don't you need one to pay taxes? (I think it's a right to have one and banks must offer a free option.)