Right, so, let us say that there is an ambulance service. Should everyone who has paid up for this service have to carry a certificate to say so? What if you choose not to pay and are then involved in an accident? Or what if you have paid but your certificate wasn't on you at the time? We wouldn't want to accidentally save the life of someone who had not contributed, now, would we?
And what if you're a rich bastard who is refusing to pay up. PAY UP, rich bastard, or we'll come and take you down.
You see what you don't seem to realise is that your vision of a society is more authoritarian, more restrictive, and more rule-ridden than a society with communal provision. It is communal, universal provision that gives people the space to thrive. In your society there would be no space for dissent or experiments in alternative living because everyone would be furiously conforming in order not to go under.