1. It seems to me that all the photos are of roughly "maximum congestion" of each vehicle type. So the cars are pictured as if they're stopped at a light or in heavy traffic, while if they we traveling at 50mph I'd hope for much, much more following distance. So yes, the bikes would have somewhat more distance between them if they were moving, but that seems fair to me, as the cars would too.

2. I don't want cars to pass me within a few feet. That doesn't mean I feel unsafe when riding within that same distance of other cyclists. The relative speed is much lower, the mass is much lower, etc. Similarly, I will happily ride much closer to an immobile object (e.g. a curb) than I would like someone to pass me at 40mph. So I think the space taken up by a moving bicycle is larger than the bike itself, sure, but absolutely no way is it anywhere close to the size of a car plus following distance plus safety buffer.