Reverse search founds a fountain but cannot found a park

I have identified a strange behavior with the reverse search at Nominatim. When the search with lat and lng hits a park, it goes to the closest point (usually an address out of the park) however if the location hits the fountain it works fine.

why Nominatim cannot return a Park ???

check it here:
1 - click on the park
2 - click on the fountain: