Well there are new classes of idiots I see pretty frequently - a typical tesla driver going 90 in 120 region of highway without any reason, presumably saving last bits of battery (that has at least some rationale, if they do it due to ie fear then they should not be driving or having license).
Over say 50km part of highway, maybe 2000 cars need to overtake such almost stationary object (to regular traffic which generally moves exactly at the speed limit). Fine if you have 3+ lanes, but most highways in Europe have 2 only. Then you have all the trucks, buses and rest of traffic trying to overtake via that 1 free lane, which in heavier (but still cca smooth) traffic will create a massive moving traffic jam immediately.
If I didn't see this every other day (and for some reasons its 90% tesla drivers where I live and rest is caravans) I wouldn't believe it to be so common, but it is. Summer now makes it even worse with all holiday drivers.