When Tesla was building out their network, 800V cars were not common. Even now most EVs out there are Teslas or other 400V vehicles. And Tesla is building out 800V chargers soon, and they'll probably move all their vehicles to 800V as well. What more can we expect from them?
We can expect better chargers with higher voltages, longer cables, standard plugs, standard protocol, all EV brand support, and contactless, no app payment.
The V4 is a step in the right direction and is nearly there except for the voltage problem:
Tesla 'must' do nothing. They do what is correct for them. Building 'better' chargers isn't hard. Building 10000s of better chargers is hard. There have been a wealth of alternative charger companies for a while, and having an example that works isn't that hard. Tesla however has to scale and deploy those charges in huge volumes.
And this is specially true if you want to make stations that have more then a low number of chargers. Because the connection to the local grid becomes a huge problem, and this problem is increased is you move to higher voltage.
Tesla moves at the pace of the market, and their own cars. Not at a pace that to enable Hyundai to make as much money as possible without investing themselves.
Hyundai should be grateful Tesla opened their charges at all. Because actual 350kW chargers are incredibly rare and broken incredibly often.
First of all, better infrastructure doesn't just mean faster chargers.
Second, Tesla is a private company that want to make profit. Developing better infrastructure is not their primary goal.
Tesla builds its own charger for its own network that charges cars that they know. They don't need to sell superchargers to other networks or costumers.
Tesla has the technical capability of building 400kw charges, they build even faster charger for the Semi. But it just doesn't strategically make sense to build those kinds of chargers.
Take make about 3000 DC Fast Chargers per Quarter, they will upgrade those to 350kw/h at some point, and then higher then that eventually. But only if they can continue to build and deploy 3000 or more of them per quarter. The 'how many per Quarter' is actually the import number.
https://www.youtube.com/watch?v=sEJ2KtzMeh8
Telsa's chargers don't work well with 800 volt cars. It would be better if they supported higher voltages like other CCS chargers do.