There are plenty of good car drivers out there, as a biker I can agree.
There are a number of idiot bikers too, I can agree on that.
The perceptions arise just because of numbers.
One percent of car drivers is a huge number of idiots(random estimate based on absolutely no evidence at all), and while you as a reasonable driver will notice the bad bike riders, and remember them, they are actually so few in comparison that it is quite easy to remember them all.
By contrast, can you remember, as a car driver, all the other idiot car drivers that did something stupid, along with the truck driver, taxi drivers etc etc?
Nope you can’t remember them all, because you come across so many of them.
Your brain automatically flushes them out of your memory, otherwise it would simply be data overload.
Even bikers can’t remeber all the idiots, because the idiots are just a matter of routine, and a good few of them are just folk who are having a bad day, mistakes, or on a tight schedule etc.
As a car driver, you must surely see a large number of other car drivers doing almost anything except putting their attention where it belongs.
You will not see too many bike riders reaching for the radio/mp3/sandwich, road map/mobile phone/lighting up a cigarette.
I daresay if it were possible for a bike rider to do any of these things then there would be some who would, but the reality is that the bike rider is much more likely to look where they are going, and where you are going too and as a result they can make moves that require fine timing - the problem is that they sometimes get it wrong, fortunately most car drivers are good enough.
I suggest to the OP that they try count up the number of car drivers committing a moving traffic offence, and in London especially a static traffic offence such as dangerous parking.
You’ll find you lose count long before you get halfway to your destination.