Thanks for answering

> Because many map providers include it in their maps and present it as parking space without labelling it as private and users think they can park here.

This is NEVER a reason to delete data. Possible solutions for such problems are adding more data (details like access), fixing map providers, teaching users.

> without labelling it as private 

Because there wasn't any `access` added on this parking. So data consumers have to guess access public,private,customerstime-limited,... or use defaults.

> Do you want to include every private parking space behind every house in OSM

There is a difference between adding data and keeping (valid) data. For keeping valid data, that can easily be verified OTG, the answer is always yes. For adding data the answer is yes if it has a reasonable size and can be easily verified OTG.
