Tangentially, why won't computerized maps - e.g., Apple Maps, Google, etc. - show a scale? Generally they'll show one as you pinch/zoom, but it disappears when you release your fingers.

Sometimes I just want to eyeball distances, and not plug in addresses and request routes for everything.

I know not everyone always wants it, but a scale is a fundamental feature of mapping! Scale almost defines mapping.

Edit: One reason I ask is because I suspect some technical limitation.

I thought it'd be cool if the scale were shown by some channel, like coloring roads (pink at neighborhood scale, blue, green as you zoom out) so you could intuit the scale at a glance.

With map simplification and symbolic markers (roads are the same thickness at multiple scales) it can be really hard to figure out distances. I was once going to a less populated area, based on my local intuition I thought the distance between two locations was a maybe 30m walk max if I missed the bus, but it turned out it was a 3h walk.

It’s purely a UI thing, the same (misguided) reason scrollbars disappear.