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.