To be honest, the only thing that really grinds my gears is for what ever reason 90+% of people fail to understand who queueing in all lanes and merge in turn.
Nope let’s all queue in lane 1 and make the tailback 3x longer than it needs to be blocking junctions further back on the carriageway. Then you have those who think they are really clever and straddle two lanes to actively block the other lane.
A topic which has been done to death many times already but as I've mentioned before - older versions of the highway code, when there were far less multi-lane carriageways and far less traffic on the road while not having specific rules for merging tended to encourage forming an orderly queue in good time, getting over to the left lane early unless directed by a policeman or other persons authorised to direct traffic to do otherwise. People of that generation tended to hand on that kind of approach to the generation(s) which came after them and until around 2007 IIRC there was no specific guidance in the highway code, after the removal of the guidance circa 50s and 60s or so, and it was only properly clarified in a more recent update.
Many many people are ignorant of the update to section 134:
You should follow the signs and road markings and get into the lane as directed. In congested road conditions do not change lanes unnecessarily. Merging in turn is recommended but only if safe and appropriate when vehicles are travelling at a very low speed, e.g. when approaching road works or a road traffic incident. It is not recommended at high speed.
Whether more awareness of it would make a difference is up for debate but nothing will change while a vast amount of people on the road don't even realise it has changed in the last few years. Doesn't help that few places where it would be appropriate are properly signed anyhow but a lot of people don't do it even when it is. More recently there have been some changes to road layouts where the designer/planner has obviously gone with the assumption people will merge in turn and it just causes chaos because the road can't cope with the way people use it instead. I just have to facepalm at the stupidity of the planners ultimately though.
Problem is the odd person doing it properly generally causes more issues than it solves and just looks like pushing in and being rude anyhow regardless so it doesn't solve anything.
PS I've had this conversation with professional drivers and even driving instructors who weren't aware... more so than many other changes it has been poorly telegraphed or handled.