I am not sure, non Tesla's would like to use them or try to use them are the criteria they use to decide on opening up to other cars . I assume it is more like either
a)low utilisation
or
b)they had to do a deal to get permission to install them in the first place.
or
c) its a new site so no one can complain they have worse access than they had before since a shared site is better than no site.
Expansion usually equals existing excess demand and opening up could make matters worse ( for Tesla owners) even if there are more stalls, something they have generally managed to avoid so far. We have not had the floods of complaints of people blocked by an ID3 taking up two stalls etc that everyone was worried about so they seem to be walking that tightrope pretty well so far I think