I suppose it's the lack of exposure to museums I find shocking more than anything else. I grew up visiting museums regularly so it's so alien to imagine otherwise.
And I find it shocking that some people can't comprehend the idea that museums are not always conveniently accessible for regular "exposure" so they are seen as a treat/day out rather than a regular activity.
I live in a town in the Lake District, there are lots of little museums in the Lakes but almost none are free entry and pretty much all require you to have a car.
In our town there is one free museum and an EH site (£15 for a family pass). It is a working class town with very little to draw holiday makers so even the £15 for a family ticket can be beyond some families' reach (and most local schools take the kids to both sites as school trips so children often aren't that interested in going repeatedly).
To get to any other museums you need to be heading to Lancaster/Manchester or into the Lakes ... but that all costs money and generally relies on you having a car if you go to the Lakes as the buses/trains are dire.
If I wanted to take DD to Manchester to go to the free Museum of Science, as I don't have a car (we don't need one in our town as most things are walkable, we live on good bus routes to work/town and DDs school is round the corner) we would have to get the train, which would cost at least £30 return (If booked 12 weeks in advance to get the cheap fares) and be a 5hr round trip if all trains are running on time and that's before drinks/lunch/magazine for the train (DD is good but 2.5 hrs straight on a train is a long time to sit without some sort of distraction) etc.
So the "free" museum can still cost a minimum of £50 a trip, and as a single parent who works in a retail job, I just don't have the means for that every month, never mind every week.