The answer is pretty simple - the moment authorities start saying "well, natural immunity is probably just as good as vaccination, we'll accept that as equal to vaccination for passport purposes", a huge segment of the population who's on the fence about getting the vaccine might just opt to wait until they're infected naturally, or, even worse, get infected purposefully (EG, chicken pox parties). Which leads to more…
How can getting the vaccine be the appropriate course of action when 4,000 people have died from it, according to the CDC themselves? I am talking specifically about people who already have been infected with the virus and have survived.
Ok, though, let's talk about people who already had COVID. Did they actually have COVID, as in, did they test positive, or did they just feel really sick and think they had it? Have they had recent antibody tests? Did those tests show that they have antibody levels that would give them protection (including against delta) comparable to a vaccine? Have they consulted a medical professional about this? If it's "yes" to those questions, great, probably no need to get vaccinated. I have no problem with that. But the "I got sick so I'm immmune" stuff I hear constantly sounds more like a hope than something the people who say it have actually researched and been tested for.