I disagree with vaccine passports in principle but accept that there are some cases where they are required such as travelling abroad (which is not in our control).
I suspect the logic of nightclubs etc is that its another carrot to ensure the young get vaccinated as i think i read currently 35% of under 30s are unvaccinated. If by September that number is say 1 or 2%, i suspect that passports will be quietly dropped.
However, that still doesnt explain why nightclubs or other large events are safe now but not in two months