We don't appreciate its meaning anymore, but cash is literally the only anonymous payment method you can have in this lifetime, and people in Germany tend NOT to trust any entity/company/government holding your data for no particular purpose.
The downside of this is the split brain problem that you have with distributed systems: a state knows something about you that another state maybe doesn't, which leads to "interesting" things like illegal people having multiple identities in several states, etc. Weird s**.