One major reason for the reluctance is that nobody makes any money off of natural immunity. From Jon Sanders at aier.org:
If you’re among those of us who aren’t tribally invested in Covid politics but would like good information about when life will resume as normal, chances are you’re interested in herd immunity. You’re likely not interested in having to rely on the Internet Archive for good information on herd immunity. Alas, it’s become a go-to place for retrieving, as it were, previously published information on herd immunity that became inconvenient post-vaccine and then virtually Memory-Holed.
Over the past 15 months, the litany of Experts’ True Facts and Science regarding various aspects of SARS-CoV-2 has changed more often than the starting lineup of a bad minor league ball club. Covid-19 is spread by droplets, especially from asymptomatic people, until one day it was airborne all along and people who weren’t sick in all likelihood weren’t even sick. Stay at home, you’re safer indoors, even stay away from parks and beaches; well, actually, outdoors is the place to be. Masks don’t work against viruses and are actually unhealthy to wear if you’re not sick, then suddenly they did work and without one you might as well be shooting people. Everyone knows and PolitiFact verified that the virus couldn’t have been created in the prominent infectious disease lab doing gain-of-function research on coronaviruses in bats coincidentally at Covid Ground Zero until, one day, PolitiFact had to retract the entire “Pants on Fire!” article. And so forth.