These edits of yours are really lame:

How will the previously infected prove it? Will they willfully submit to testing when asked? Who will pay for that testing since it is about 20x-30x the cost of a vaccine? And that doesn't even account for the infrastructure and manpower costs needed for mass antibody testing.

Why not stick a needle in their arm and be done with it? It's safe and effective, especially if they already had it.

You don't live in reality if you think there are viable alternatives to mass vaccination.