Question Why Are Tour Groups Still Requiring Covid Vax and Tests?

I've noticed that most tour groups are still requiring the Covid vaccine and tests, even though many places have relaxed their restrictions. Does anyone know why this is still a thing? I'm trying to plan a trip and it's a bit confusing navigating all these requirements. Are they just being extra cautious, or is there a specific reason they're sticking to these rules? Would love to hear if anyone has insights or has dealt with this recently.