The first thing you need to know about is SAE J1772.
If you are on PlugShare, you'll see these everywhere. Everywhere. They are NOT fast chargers, unless they have some additional qualifiers on them, which, short form, they don't, yet, but they may soon have words like "ComboCharger" or "CCS" or something along those lines. AC chargers/fast chargers are sort of forever split because different regions have done AC differently, however, DC is DC is DC so in theory you could at least make the DC part a shared protocol (might be the wrong word).
I think that we can expect in the future to see a lot of Fast Charge stations that have Chademo (Nissan) and CCS hookups (which only BMW would currently make use of), in much the same way that each fuel pump currently has a bunch of hoses for different grades of fuel, and maybe a really different looking hose that is labeled Diesel. Open question how Tesla interacts with all of this.
ETA: And while all Nissan dealers seem to have some sort of charging station, they don't all -- maybe not even most -- have the Chademo fast charger. Nissan is exploiting the dealer network to provide a comparable service to the Tesla network:
There really does seem to be a West Coast bias, but that's not surprising.