Except, the current choice of vaccines appear to have issues offering broad sterilizing immunity. Vaccinated people are still "getting" COVID Delta, often with zero symptoms, but are still spreading it.
So they're not even all that good at providing the one thing companies may argue is necessary to go back-to-work; stopping spread. Similar with cruise lines and airplanes requiring it. Yes, the vaccines are very good at saving peoples' lives, but industry doesn't care about that, and it alone is not a good enough reason to mandate it.
You say everyone needs to get vaccinated so we can protect the people who can't get the vaccine or for whom it doesn't work. I have very bad news for you; the vaccine won't help. You can still get COVID, and you can still spread it to your four year old. I can still get it and spread it to my immunocompromised sister. It sucks. That's the reality we live in.