Its not hard to understand at all, your house, your prerogative, I just find it fascinating peoples appetite for risk is so different. In my scenario above, I'd simply insist on mask, gloves and basic health status, then if I felt compelled to do so, run through the glen20 (or whatever sanitiser I trust) where the tradesman was working.
Maybe its my risk management mentality coming out, everything in life is a risk, some you can eliminate, some you can minimise and others you have to manage with appropriate controls. Right now, in the south island, there is no COVID, will that situation change, absolutely 100% yes, but for now, I am happy to live in a "normal" way. If there was COVID in the community (as the case in Auckland / Waikato) then how I approach things would likely be different.
The risk to me is quite low, I'm vaccinated. So I may pick up a case of COVID from someone and have minimal/no symptoms. However, there will come a time when we're living with COVID that I won't be required to self isolate. So I'll be out the community, perhaps completely unaware that I have COVID, spreading it further. One of those people that I spread it to may be immuno-compromised and were not able to protect themselves with the vaccine.
That's a risk that I'm not prepared to take. So you're right, it is partly about risk, but not to me.
The other part of it is that I simply despise anti-vaxxers and want absolutely nothing to do with them. Part of me is grateful for COVID as it allows me to identify them easier and eliminate them from my life.