The parking space was mapped 9 years ago, probably because it's visible on the ground.
Other things might not be mapped (like other parking spaces) because no-one took the time to map them.

The `access=private` tag is correct; I would *not* delete the parking, as it is is so-called verifiable and anyone can add it back to the map: https://wiki.openstreetmap.org/wiki/Verifiability