Nissan provided some incentive for dealers to install charging stations, but I don't believe there's any requirement to make them available to the public. .
One of the employees at one of the dealerships here in this area said that Nissan paid half the cost of the DCQC, including installation- about $50,000 I think.
There are 4 Nissan dealerships in this area and I've charged at 3 of them. I've always had good luck- 3 of them have DCQC stations, including the one near my house. I've used it a few times when my daily driving has exceeded my charge-comfort-level. I also sent a message to them letting them know that I appreciated them providing it for free for the EV community and that it was a big help for me.
Unfortunately the dealerships here all have gates & the stations are only accessible during business hours. That's a minor inconvenience for me, as there are many L2 chargers around that I can use as an alternative, if necessary.