I too get a bit frustrated with drivers who yield when they have the right of way. It basically just confuses the situation. I certainly roll many stop signs. I'll see a car pull up well before me at a 4-way stop, and they could clearly get through the intersection before I even get there. So, no danger even if I didn't even slow down. But they don't proceed when they should. I of course then have to stop as well because they have the right of way, having gotten there well before me. And of course, I don't really know that they are yielding to me. They could just be looking at their phone or car radio. If they had just proceeded normally, they would have been past and I could have slow rolled the stop sign and not have to put a foot down.
I can also appreciate that some drivers may have experience with cyclists who ride as if trying to commit suicide. I occasional see a few. The types that blow stops signs at a speed and situation that it is only luck that a car wasn't coming along.
I also agree that in general, cyclist are much less common in most areas than cars. So, most drivers just don't have experience with cyclists and many cyclist are rather unpredictable. So the drivers just stop and let the cyclist get the hell out of the way. It's hard to argue against that logic.
However, as much as this can be frustrating, I much prefer the overly cautious driver to the opposite.