The natural immune protection that develops after a SARS-CoV-2 infection offers considerably more of a shield against the Delta variant of the pandemic coronavirus than two doses of the Pfizer-BioNTech vaccine, according to a large Israeli study that some scientists wish came with a “Don’t try this at home” label.
Over 100 million Americans already fall into this bucket of having these antibodies. Why should they care about something that doesn't matter? Reinfection is very rare - so these people are not a risk to anyone.
Even if you've had covid already, it's not going to do any harm.