Stop signs are designed for cars - because of the built in obstructions to their sight lines (e.g. pillars, trim, maybe passengers) that a cyclist doesn’t have,

Stop signs are designed for cars - because of the built in obstructions to their sight lines (e.g. pillars, trim, maybe passengers) that a cyclist doesn’t have, the speed at which cars approach the intersection (much faster, so less time to look, plan and react), etc. But the issue for the bike (apart from the fact that stop signs mostly aren’t necessary even when they are for cars) is that it takes much longer for a cyclist to take off, so they spend longer on what you could call the ‘danger zone’ of the intersection (where they are crossing the path of traffic) if they have to stop.