It happens with any subgroup. Bad apples spoil the bunch and all that. Heck, a lot of bicyclists in this very thread make the same complaint about car drivers and act as if they're all a monolith who only care about running down as many bikes as possible, even though at least some percentage of us do try very hard to be safe and considerate while driving.
Somewhere else in this thread, bicyclists are complaining about cars who specifically try to wave them on to go first. While I can understand why this might not always be what they want, this seems like a generally good situation - the car driver is aware of the bicyclist and is attempting to do the right thing by indicating that they've noted the presence of the bicyclist and also trying to be courteous. I've done this myself from time to time and I assumed I was being a good driving citizen, but perhaps I was wrong.
I would hope that we can all agree that there are a subset of drivers who are reckless and dangerous, and there are a subset of bicyclists who are also reckless and dangerous. We have the same issue with boaters, personal watercraft, etc. Aircraft might be slightly better because of the high barrier to entry, but reckless pilots exist too. In each of these cases, the bad ones tarnish the rest.
I guess I've assumed that a bike would prefer to cross in front of me, someone who has acknowledged their presence and also happens to be blocking the lane behind me, rather than wait and take their chances with the next guy who may not be looking. Perhaps I'll reconsider that in the future. I still think I will do this in at least some circumstances, like when I see kids on bikes wanting to cross. In the case of kids I make a point to check all the traffic before waving them on and basically try to act as another set of eyes for them while they're crossing.
Somewhere else in this thread, bicyclists are complaining about cars who specifically try to wave them on to go first. While I can understand why this might not always be what they want, this seems like a generally good situation - the car driver is aware of the bicyclist and is attempting to do the right thing by indicating that they've noted the presence of the bicyclist and also trying to be courteous. I've done this myself from time to time and I assumed I was being a good driving citizen, but perhaps I was wrong.
I would hope that we can all agree that there are a subset of drivers who are reckless and dangerous, and there are a subset of bicyclists who are also reckless and dangerous. We have the same issue with boaters, personal watercraft, etc. Aircraft might be slightly better because of the high barrier to entry, but reckless pilots exist too. In each of these cases, the bad ones tarnish the rest.