>What's their energy consumption vs. a LCD?

Zero when they're not flipping, and close to zero when they are. Even under direct sunlight, to overcome which LCDs need >100W / square meter.

I don’t know about the USA but there are likely millions of them deployed around the world, and working fine.

Same problem on LCD/with the font you use though - those displays are dense, and designed around room for 'AB1234'. Confusing to have it scroll when it already rotates into some other information too.

I think Russia still does.