Don't be so sure about the risk of Government action.
The EU
DIRECTIVE 2014/94/EU contains the following requirement:
9. All recharging points accessible to the public shall also provide for the possibility for electric vehicle users to recharge on an ad hoc basis without entering into a contract with the electricity supplier or operator concerned.
That could be interpreted to require Tesla to accept other manufacturers' vehicles.
Fortunately, the
UK regulations implementing the directive keep that requirement but have a definition of "accessible to the public" that allows Tesla to carry on operating superchargers:
(2) A recharging or refuelling point is accessible to the public if it is—
(a)intended for use by members of the general public (including those situated in public car parks, whether or not those car parks are available only to consumers of specific goods or services); and
(b)not intended for—
(i)exclusive use in respect of a vehicle produced by a specific manufacturer;
(ii)use by persons engaged in specific occupations;
(iii)use by persons whilst at their place of employment (including visitors); or
(iv)exclusive use by occupiers of, or visitors to, residential premises.
This wording was not in the original directive, and other EU countries may have implemented the directive differently. At one point it was looking problematic for Tesla in Germany; I'm not sure how that got resolved.
However, Tesla are now in a reasonably good situation for the long term in Europe - with the switch to CCS connectors on the superchargers, and the forthcoming updates to the CCS spec that will allow the car to identify itself to the chargepoint and give a supercharger-like experience for billing, they have most of the pieces to allow non-Tesla cars to charge (at a punitive price) if forced to by law. Not sure what (if anything) they would do about the short cables on superchargers. And if third-party charging operators do get their act together such that superchargers are no longer so special, Tesla still have advantages in their equipment (SC v3 seems significantly superior to the kit that Ionity are installing), and a head start in ambition and branding (Ionity still messing around with 4- and 6-stall sites, while Tesla haven't installed smaller than 8 in a long while and are planning more like 32-stall for future sites).