A heuristic such as, right to speak with a human, if a) Customer pays for the service b) Service stores any data of the customer's (e.g., email provider, cloud storage provider, facebook, youtube, instagram, etc., but would need a threshold i.e., a simple throwaway comment would not have enough value to trigger, but an article, photo, or document would). c) Service acts as IdP where being locked out might result in being locked out of other services (e.g., "login with facebook/google", Okta, etc.)

I am sure there are other cases I have missed, but this should give an idea. The problem will be in defining the rules specifically enough to address your concerns, yet vaguely enough that companies will not find ways to satisfy the letter of the law while violating the spirit.

Yes, Github would fall into the categories above. If, as a result, Microsoft decided they no longer wanted to provide non-paid accounts, then so be it. Their business model was unsustainable if it could only work by abusing their users. Some things of value may be lost.

This right to speak to a human should apply to non "web" companies too.