It sounds similar to the current "standing charge" you get on UK household energy bills (don't know about the rest of Europe).

Even if you don't use any electricity you still pay a day rate (on most tariffs).

What I'd hate to see long term is if the subscription remains tied to a single supplier (i.e. I pay my subscription to Tesla, but use Ionic to charge, so pay the subscription charge and the higher rate). That will mean the decision to use a different charge point still has repercussions, and prevents the openness of the infrastructure we (society at large if we're moving full electric) really need.