I think it's mostly different variations of exactly that.
At the extreme end it's doing a bit of motorway. Usually it's nothing like the M1, but maybe a short bit joining two OK roads, or a quiet motorway with a hard shoulder that all the locals use to cycle on because its actually better (and probably safer) than the other roads, or going the wrong way down a slip road to miss out a big junction. Or it could be a 'car only' A road, which are common in Germany, Hungary and elsewhere. Or a road where cycling is allowed but which the race has banned. This might be specific tunnels, or E roads in Romania, etc.
It could also be missing out a bit of parcours.
I can't think off the top of my head any other common reasons people get penalties.
I think it's mostly different variations of exactly that.
At the extreme end it's doing a bit of motorway. Usually it's nothing like the M1, but maybe a short bit joining two OK roads, or a quiet motorway with a hard shoulder that all the locals use to cycle on because its actually better (and probably safer) than the other roads, or going the wrong way down a slip road to miss out a big junction. Or it could be a 'car only' A road, which are common in Germany, Hungary and elsewhere. Or a road where cycling is allowed but which the race has banned. This might be specific tunnels, or E roads in Romania, etc.
It could also be missing out a bit of parcours.
I can't think off the top of my head any other common reasons people get penalties.