Different series have different opinions as to what is acceptable and what isnt, the BTCC has always been fairly open to driver contact and agressive racing, the DTM on the other hand doesnt like too much contact going on (nor do Audi it seems hehe) and they'll happily hand out penalties for something BTCC see's every single race.
There does seem to be this expectancy in LFS sometimes that if someone touches your car they should be banned, typically it comes from the n00b end of the spectrum, but contact is all part and parcel of saloon car racing and provided it isnt more akin to wrecking there is nothing wrong with bumping someone up the backside or forcing your way through a corner at the other persons expense, however if that sends the other person off or causes an accident etc its a different matter, but i think it entirely depends on the level of ability as to what you can get away with, 2 very good drivers will be able to scrap (if LFS's collision detection lets them!) just fine, but the further down the line you go the probability of an accident increases, mainly because of a mix of not enough driver awareness, car control and ability to drive side by side. I dont recall any complaints being made or held (i know you cant have any held if theres none made :razz
in the top division last time round, there was certainly incidents in there but i think its handled differently by the drivers involved, and typically those drivers know if what they're about to do is sensible before getting to the point of no return.Accidents will still happen, you see it in real life and they're no n00bs, and sometimes people need a ticking off. Still, people should take onboard something from the weekends F1 race in Japan, 2 drivers pretty much driving the other off the track on the last half lap, corner for corner neither giving an inch, and after the race they shook hands and laughed about it.
