And even if we do get testing - and a vaccine! - how do I know that you have done it? A tattoo on your forehead? An armband? A scarlet letter pinned to your lettermen jacket? (That you could have purchased from Etsy, and NOT have gotten from the doctor that stuck you with the vaccine needle?) Oh. Ok. A new mark on your Driver's License. "Blue eyes; Organ donor; COVID Vaccine 10/2020". Which also has the new RFID card in it, so now the vaccine IS actually an RFID tag, and all the loonies refuse to get it, and now we have 30% of the population with the vaccine which isn't nearly enough... And we have all the medical solutions in place, but none of the social ones. We are so very fucked.
Vaccine records are kept by States in which the vaccine was administered (it's very easy to call your Heath dept to get your complete vaccination record going back to when you were born), so it's conceivable that if necessary the government could say something like, "You can't use public services X, Y, or Z without getting this vaccine." They do that with schools to varying degrees and it works well in places where they enforce it (i.e. not on the West coast). But I don't think it would come to that. I think that the vast majority of people will see a vaccine (provided it's safe and effective) as being in their own selfish interest and therefore get it voluntarily. I will. Most people I've talked to will. We all just want to get back to normal, and if that's the path, people will take it. We don't need 100%.
But how do I, the bouncer at the door of my local bar, know that you, some schmuck that walked up and wants to come in, have had the vaccine? What proof can you show me, that will make me comfortable you aren't going to come into my place of business and turn it into a superspreader event? The government can say anything it wants... enforcement requires transparency and data, and I don't see how that part is going to work.
It's a numbers game. There won't be any super spreader events if sufficient numbers of people are vaccinated. We just have to trust that the vast majority of people are going to act in their own best interest, which in this case is also in society's interest. Of course, convincing people what their best interest is is often challenging, no doubt.