Only time I would willing do this stuff is if it was an older person, or a mom with a baby. I worked in a college town, and it drove me crazy when 20 year old guys would sit and watch me do basic things on their car. I remember some 40-50 year old guy came in and asked if we installed batteries. I started with the line “We’re not a shop, but if it’s easy and no issues I could do it”. I hardly got past “we’re not a shop” when he stormed out yelling “Nope, Nope” with his hands in the air.
I would start offering to teach them. I handed them all the tools and went out and showed them. Very rarely did someone complain about it.