In aviation, more maneuverable aircraft yield right-of-way to less maneuverable aircraft. Though not actually codified, this is generally true in automotive. No one argues with the 18-wheeler. Then it breaks down when cyclists expect everyone to move for them (and this is the exact argument another gentlemen here was making the other day when claiming it's the driver's responsibility to adjust *their* behavior to accommodate cyclists).
Maybe motorcycles and bicycles should also be automated. I mean, fair is fair.
It's not just bicycles, the practice breaks down for anything smaller than a car, like mopeds and of course pedestrians.
I suspect it has to do with relative speeds, and available room to manoeuvre. A car and an 18 wheeler are wildly different masses but can move at the same speed on the roadway. A smaller plane might be slower than a bigger one, but can manoeuvre better and it isn't restricted to 2 dimensions for avoiding a collision.
For the slower, smaller things on the road: they may technically be more manoeuvrable but the speed differences make it harder to get out of the way in time. Bikes/mopeds are restricted to veering left and right, with curb or barrier limiting choices further. Pedestrians have more freedom of movement but even less speed.
As for the gentleman saying drivers have to adjust their behaviour to accommodate cyclists: as you noted cyclists aren't angels, but generally speaking, he's not wrong. Bikes legally belong on roads, so car drivers do in fact have to accommodate them, whether it's to pass them, turning at intersections... heck, even opening driver-side doors after parking on on a street can be deadly (New York City taxis have stickers asking clients to exit passenger-side for this very reason). In many places without dedicated bike lanes, bikes are even legally allowed (and sometimes encouraged) to take the entire lane, the same way a horse-drawn carriage or tractor does, so cars would have to move an entire lane to pass. Most cyclists are reluctant to take advantage of this last privilege because they do recognize the inconveniences they've already put on drivers and don't want to cause even more grief, but they reduce own their safety by not doing so.