This stuff happens in almost every level all the way up to A+/S
The only time I've rarely seen weaving, or pushing people around, or basically any dirty stuff is in the very top splits for the FIA championship when it's a main season & there's a bunch of the supernerd eSports kids in there on their wheels. They tend to try be as clean as possible often because I think being dirty could maybe harm their chances of being invited to the tournaments in person or something.
Regular A+ lobbies though, especially just weekly races... Yea there's tonnes of dirty stuff going on & some of its for good reason too.
A lot of what I see is things like revenge punts, or people feeling disrespected in some way & deciding to wreck a guy because of it. Even things like previous beef from other lobbies spilling over into new lobbies.
One thing I've done & seen others do is crash out no-etoppers for rave C. & While I get that it's part of racing, in a video game I simply won't accept losing to a no-stopper. Mainly because I think it's a cowardly, cheap, low skill way to win. Short shifting & saving fuel is not difficult, it's anti-racing & anti-fun & there's nothing more annoying than when you've battled like crazy with maybe 2 other guys in the top 4, going purple & pulling off awesome racecraft, only to lose the win to someone that was too afraid to actually race & instead chose the most overpowered, easymode way to win a race.
No stopping, needs to tank performance more. The difference between no-stopping & going flat out should always marginally benefit the guy that pits & goes flat out, taking all the risk, racing on the edge. The risk is that if he makes mistakes , the no-stop strategy starts to come in to play & be viable... But that if you have a flawless flat out race you should have a significantly lower race time.
Pretty sure the fastest race time I had this week for Race C was 19:01 with a FL of 1.24.8 on controller. The turd that won was on a wheel doing a no-stop & had a 18:55. Ridiculous.
I've always hated no-etoppers in GTS & this, & it'll continue to be one of those things that I shamelessly bin people off for doing because I just think it's absolutely the weakest thing you can & is Anti-fun... & I'm in the A+ lobbies so yeah.
The point of this rant was there are many variables as to why people do dirty things, & almost none of them are because they don't understand the rules or need some kind of extra help... It's because we know the consequences & will do it anyway if it's worth it or it justifies our own reasoning.
It is after all, a game