I'm not a fan of vaccination passports, it achieves not much tangible other than to push a few to get vaccinated, and maybe to maintain vaccination. With regard to a company mandating it, that is tangible, the cost of sick leave of an unvaccinated staff member is exactly relatable to the efficacy of the vaccine. If the staff member is 80% less likely to get symptomatic covid, that's 80% less chance of having 2 weeks+ sick leave to pay out. Then there's the recovery cost of a crew getting sick on a layover, possible law suits if someone gets sick on a flight etc etc. There is direct measurable cost saving to the bean counters for vaccinated vs not, and you can't argue with that.