Yesterday a car came up on me in a low speed zone, passed me in slow motion, even though I was going 2 mph under the speed limit, and only 100 feet from a stop sign. I suppose in retrospect I could have hit the brakes and let them get in front, but there really wasn't time. So, we pretty much reached the stop sign at the same time, with the SUV in the opposite lane. Nobody else around, fortunately. I had to LOL, in spite of everything. And they were just diddling along, obviously didn't have to be anywhere in a hurry.
Motorists can easily get into a "bicycle = slow (as in 3-5 mph slow), must pass them at all costs or the molten lava will catch me/I don't know how to use a brake pedal/I just want to get somewhere without all the hassle" mindset. This habitual, subconscious mindset has taken over so any critical thinking doesn't come into play: "Stop sign ahead, low speed limit, I'm not in a hurry, trike is going nearly as fast as I am, I'll just wait until after the stop sign then pass them on the uphill, because I am driving a big vehicle." (They really should issue special licenses for people to drive SUVs but that isn't going to happen)