In Germany we have a compulsion to use airfields. It's one of the elementary aerial laws. That means that any offside landing ( with all kinds of a/c !!! ) needs an official permit. For special purposes you can get a general permission. All professional helicopter operators have a general permission according to their proposals.
You can get a general permission as a commercial pilot also for private or executive flights.
You can get a permission for an offside landing (general or specific) also as a private pilot, provided that you have enough flight experience, the owner of the area and the local police or mayor agrees to.
Germany is a federal republic. At each country is a special authorithy responsible for the permissions. And in each country exists different views to the topic.
It's possible that the local authority insists of a special checkride with one of the their examiners or that you have at minimum 300 flighthours... Depends on the officer... You must demonstrate your qualification by logbook, checkride or... or... !
Reasons:
Dense population, noise, private property, environment protection, lot of airspace restriction due to the intensive traffic, ...
And most german private helicopter pilots are very unexperienced and bad trained due to the very expensive helicopter costs ( 1h R 22 > 300€ + dues, Jetranger > 650€ ), restrictions and flying not more than 5-10 flighthours each year. That caused a lot of accidents. Therefore the authorities checking strictly.