In response to the OP’s question I think there’s an element of power and changing power on the roads going on here.
cars have been mass usage from 1950s onwards. Most people alive today therefore know nothing other then being able to drive where they want, when they want, without having to worry too much about cyclists.
There are more cyclists now which means a change in driver behaviour is necessary – primarily having to think a little more about others.
I think the core of the bad attitude to cyclists is simply this, it means the balance of power on the roads has changed.
When the car driving masses either ride themselves or get used to this change, things should be better. But for now, we’re in a transition period whilst car drivers will need to adapt their expectations and behaviour. Some are ok to do this, some are like small children and throwing a tantrum (or an egg!)
I don’t think it helps that modern cars cocoon drivers from the risks they take, and so they have little awareness of the riskiness of their driving style for others.
I think the required kind of culture change we’re expecting will take 10+ years to come through… better enforcement of current law would help IMO