"contact data" is already a pretty nebulous term. If my experience with European business websites is anything to go by, this is not the sort of requirement that the GP is talking about.
I said "contact data" as shorthand for the specific requirements, since I would have to look them up. And yes, the "Impressumpflicht" the parent talks about is exactly that, in a very strict form.
EDIT: To elaborate, the EU e-commerce directive from 2000 requires all member states to have laws that require commercial sites to have at least name of the entity, physical mailing address, business registration IDs if applicable, e-mail and VAT ID published. Since it's only a directive, the details vary from country to country. E.g. France requires also listing a phone number and an actual person responsible for site content.
I'm not talking about the German laws. Germany is not the right example for how the EU works because in cases like this they are almost always much, much stricter than everyone else. The requirements you noted for a business in the more general case (EU-wide, in other words) are much more lax.
