Some other countries have this, so the software is capable of it. My guess is they have standards so far as what sites they will make available, and this involves manual configuration and negotiation with the network operator.
For example, they probably wouldn't want to include a lone 50 kW unit. The risk being that vehicles will navigate to it and it will be unavailable for various reasons (in use, faulty, ICE'ed etc) and if they can use it, a new Tesla own may not understand why it is slower than a supercharger.
On the other hand, a multi-stall 350 kW site would be much closer to the standards which Tesla would deem good enough for inclusion.