> becomes congested with no time/space gaps between vehicles, is worse for pedestrians

Why? This feels like it's assuming pedestrians share the street with vehicles, but besides the US and some other places, don't most "modern" countries have separate pavements/streets for pedestrians? Besides in the country-side, vehicles and pedestrians don't generally share the road in populated areas here in Spain. For crossing roads outside cities, building a pedestrian tunnel below or a bridge above seems to preferred here, except in the cases where it isn't possible, and in cities obviously.

The traffic has to yield to pedestrians when entering and exiting a roundabout, period.

No it isn't unless all driver all break the law and don't stop for waiting pedestrians.