alt Hacker NewsIn Germany you have to keep your records for 8 years as a commercial entity, and 8 years is a lot of customers you deal with, if you work with private customers.
If your primary focus as an electrician, plumber or other tradesperson is SME or industry, of course, then there is far less customers.
No plumber I know is able to deal with more than a thousand different clients in eight years. This is so absolutely unrealistic it's laughable.