A few points...
First they are STILL Tesla proprietary tech even if they allow other vehicles to use them. Why is this important to point out? Because they could always disable access to other car makes, and no one else can build them without their approval.
Yes. However, non-Tesla electric car owners have managed fine so far without access to Teslas superchargers. Access gives them more options, though, and puts some money in Tesla's pockets.
Secondly, if a third party does start building out equivalent stations... how do they recoup their costs? Remember Tesla is building them as an incentive for people to buy Tesla's. Getting access to a high voltage line from the local power company is VERY expensive like 7 or even 8 figures depending on distance form the nearest transformer. The power company is also going to have to start spending capital to increase capacity.
Tesla built them as incentive back when people needed incentives to buy their cars. Those incentives are now being rolled back, as they're not needed as much anymore.
Note me buying two Teslas without access to one.
And they recoup their costs by selling electricity. Most chargers in Norway are run by electric companies. Selling electricity is what they do.
But as more and more electric cars are hitting the roads in Norway, gas station chains have also opened up chargers at most of their stations.
A total of 15 stations and 158 individual Superchargers are part of the pilot in the UK, making it the biggest fast-charging network of the country. Tesla operates two high power chargers in the UK, V2 units with 150kW and V3 units with a power output of 250kW. Thanks to the pilot expansion the Supercharger network has also become the biggest fast charging network (with units of 150 kW+) in Europe. The newly open chargers represent 25% of the brand’s 650 charger capacity in the UK.
So for the entire United Kingdom there are just 650 total supercharging "plugs" and just 158 of them are available to non-Teslas.... that sounds like a tiny little pittance that will not even be close to sufficient for a country that size to switch to full electric vehicles.
Here's a map where you can zoom out and see all the charging stations in Norway, Tesla and non-Tesla:
https://www.ladestasjoner.no/kart/
You can zoom in and click them, and see what company they belong to.
They are in the thousands, and most are not Tesla.
Also, I'm genuinely curious, how fast can you charge at these other stations, what are there details (ie who owns them), what does it cost to charge?
The ones in my area, northwestern Norway, in a city with 70 000 people, they range from 50kW to 300kW. The 300kW ones are built by Circle K, and charge faster than my Teslas can recieve. The nearest Tesla supercharger is only 250kW.
The older ones (remember, Norway starting adopting electric cars over 10 years ago now - 1 in 6 cars on Norwegian roads are electric, and 80% of new cars sold are electric) are the slowest, but the ones being built these days easy rival or surpass Tesla's charging speed.
As I said, they are mostly owned by electric companies or gas station chains.
Pricing varies, but charging a Tesla at a Tesla station will always be the cheapest.
But the coverage is so good now, that even if Tesla shut down all their superchargers, most people would do just fine without.
ETA: while I think electric cars are a great idea for local transport, when most people can just home charge, I remain very skeptical that they are the best way forward for long distance traveling.
I don't know why. I know plenty of people who have travelled Europe with their electric cars. This summer, I saw lots of Teslas in my town with foreign plates - from Spain, Italy, France, Estonia..
The longest drive I've had is from my hometown of Ålesund to Oslo, which is around 8 hours. I stopped 20 minutes halfway there, which I would have done with a fossil fuel car anyway. Charging while getting food.
If I had a choice to drive my Tesla or a fossil fuel car of my choice across Europe, I wouldn't even hestitate to choose the Tesla.