In the UK this is actually enforced, and we have ASLs (https://en.wikipedia.org/wiki/Advanced_stop_line) allowing cyclists to move in front of other traffic at junctions, and start ahead of them. Is this sort of thing not part of the road system i9n the US?
It's quite rare here in US, I've only encountered it sporadically near some universities. I think they make a lot of sense and wish they were common. Typically here there is enough room for a bicycle and then some ahead of the stopped cars, so it makes little sense to me why the extra markings are not painted on the road - possibly lack of familiarity?
