To a point I agree, it is a pain in the butt.
But mostly disagree for various reasons.
Not all drivers or riders are as confident as others and will drive or ride slower, and the more experinced drivers should not push anyone above their own confidence limits. There could be various reasons for them driving slower than the limits.
But I do admire a 70 old granny that passed her test donkey's years ago when cars were a lot slower and there were fewer cars on the road. And for them to venture out on today's roads, to me they deserve some respect.
You may say, they should be retrained up to todays standards.
For example, I personally am not as competent with computers and the latest mobile phones, a six year old kid could get better use out of them than me, but if a youngster said to me, you should go back to school and learn technology to keep up with the technology I would quite simply tell them to F off !!!
The roads are more to blame than road users, most of the roads we drive on were laid years ago, and simply cannot cope with the current demands. We could do with better roads to cope with todays requirements. I don't like tractors dumping tractors on the road but they can still get away with doing it, horses is another one and so are drivers travelling at 20mph less than the speed limit.
My wife is one of those who drives slower than the speed limits, she isn't the most confident driver but she is a safe driver and has been for over twenty years, but in twenty years time she will no doubt be one of those people you are talking about.
Younger drivers think they are the best drivers in the world, but havent a clue of the experience some of the older drivers have. slower and wiser?