I take my daughter- who is also vulnerable and lives in a different household- to college. The risk assessment stated we should both wear masks, sanitise hands and open windows slightly to circulate air. She takes her mask off as soon as she gets in the car but I wear mine. I guessed it was safer for me to drive her rather than go in a taxi, as I know what I am doing, I don't necessarily know what a taxi driver is up to and how many people he has in his cab all day.
SO, what I am trying to say is, we all mitigate our own risks and what some people might think OK, others don't. We really shouldn't be judging one another and certainly not our friends.