If you check the Find Us map and select "Superchargers Open to NACS" then you will see which ones are compatible and their associated 'Charging Fees for NACS EVs' rates.
1: https://www.tesla.com/findus?v=2&bounds=53.02665397538087%2C...
Some have speculated that it relates to the stall layout, but if that is the case the differences must be really subtle.
Its going to be a dance with the power engineers to evaluate the oldest sites to balance out what it may cost to upgrade the transformers feeding the site, and if the cables from the transformers to the chargers are adequate or not. Distribution devices from the transformer will need to be evaluated as well.
Simplest would be perhaps adding a 250kw charger here and there to the site, dependant on transformer capacity. This would also be the most confusing for users.
Interestingly in LAS, the tesla charging station behind Flamingo (near the monorail) has "destination (basically 240v home chargers)" chargers intermixed for adding overall vehicle capacity.
All of the 250kW chargers support full speed at all stalls. That was one of the major changes with v2+ of the supercharger.
IDK what would be confusing, they have the ability to throttle when over capacity already implemented and every car will ultimately have a charge curve that prevents them from charging from 0% -> 100% at 250kW the entire time.
I'm guessing it is the result of site negotiation between Tesla and Ford, coupled with firmware/hardware/signage changes.
Ford wants chargers where they think they'll be most likely to sell cars, and might have handed off a list to Tesla where market research showed they'd sell the most EVs and there is the worst charging infrastructure, for example.
Tesla might be u an algorithm to pick stations they think that adding smelly Ford-driving plebs to will irritate the fewest Tesla customers but still meet their contraction obligations to Ford.
There may also be agreements with the host site - malls and the like may have agreed to lease land for the chargers and spaces etc in exchange for the wealthy people the stations will bring to the area.
Ford et al are crazy to do this, frankly. Musk is incredibly unstable, extremely self-serving, and while I think Musk ultimately wants to become the Mobil/Shell/BP of electric charging, they're still competitors.
The algorithm seems to be simply which stations can transition to NACS protocol.
Malls are leasing land mostly for rent. Some are obviously more enthusiastic about it than others. Some chargers are off in the corner, out of the way. Some are front and center, placed so that the drivers can have easy access to the mall. Ford is brilliant to partner with Tesla, because the existing fleet of chargers suck, and Tesla's doesn't suck. They certainly have a contract with Tesla that assures a certain lenth of time for reliable service (e.g. Tesla won't cut off Ford drivers or do wild pricing to punish them). Tesla wants more customers - car or energy customers, doesn't matter. So seems like a win-win all around. Unclear why this is bad for Ford or Tesla.
The loser here might be the Tesla drivers, who now need to compete for space with the Ford drivers, especially since the Ford cars don't charge quite as fast as the Teslas do, and there is some friction due to the position of the charge socket.
But in the end, the increased revenue for Tesla will allow Tesla to build more chargers, which is what Tesla drivers have been enjoying anyway. So maybe ultimately it is better for everyone. Everyone, that is, except for the oil company executives.
The few v4 sites that are available do have longer cables.
It would be useful to compare to the publicly available "standard plug" chargers out there. Cars using the adapters are gaining charging options, while presumably near-future models might have access to the entire Tesla charging network.
Meanwhile, all those existing "standard" changers are going to need an upgrade...