Because cars can always turn through a crossing, this causes near misses and mayhem all the time, but I find generally that a lot of people don’t notice or just accept the car-dominance as a natural thing.
When the kids were small we taught them about these dangerous intersections calling them “surprise-red-man” crossings (sounds better in Swedish).
I’ve never been able to work out the logic of why the flashing green man should disappear on exactly those roads where they’re most needed.