[germanier]

This is in general not true and German government departments share data with different departments all the time without explicit consent of the affected citizen. This is also not a good example as there are additional legal restrictions for government departments which businesses don't need to obey.

[usr1106]

If the sharing is not required by any law they have to ask. Sometimes they do. I'm sure there are cases where they share without either of the precondition met.

[germanier]

There are cases in which sharing without asking is legal without it being required by law.

[ben_w]

GDPR is a standardisation of pre-existing national rules within the EU member states, at the time including the UK’s Data Protection Act. When I was at university, one of the examples of the scope of the Data Protection Act was a barbershop which kept hand-written (no computer involved) records of customers, and one customer used the DPA to demand to see their records and then to have those records destroyed.