This all boils down to when that station was last rehabbed. It's all part of the contractual agreements brokered between the mta, the city and the company near the exit. The MTA gets access to a part of their property and the company gains an entrance to the subway but have to maintain a portion of it.

In this case, Citi group gets access to court sq via an entrance, but have to maintain the elevators.

There's a whole bunch around the city like this. Usually privately owned entrances/escalators/and elevators have an X at the end of their unique code.