At the OP its a wider issue and from my experience SR makes no difference as to how clean a race will generally be, I consider myself more than fair as an opponent and have been SR/S a few times, Both times however I've also been knocked back to SR/B thanks to morons who can't drive and decide to use my brakes instead of going around me as well as crowding off-track.
I did however have one strangely clean race yesterday with the Ford Focus, I didn't bother to qualify because frankly I joined to drop my DR down abit, I started 9th and finished 4th, Which all things considered was pretty good, The scoreboard still showed a few people with time penalties though and this was SR/B.
You'd think people might have learnt by now that racing clean is faster than not
I'm afraid the opposite is happening, at least on some tracks, especially Interlagos. I did 5 races there today in DR.B/SR.S and all 5 the same things happened.
People bunch up naturally at the chicane go side by side, cut over the green etc, yet surviving the first corner is just the start. Now there's 2 options when you're behind a group of cars going through a corner together at slower than optimum pace as that's not possible with 2 or 3 cars next to each other. You can:
A. Hold back a bit and aim for a fast corner exit, pass the last car on the straight and fall in. This is risky as the car you just passed likely won't give you any room at the next corner and now you're trapped.
B. Aim for the inside of the apex, cut the corner a bit, brake late, use the inside car as a bumper and instantly gain 3 or more places. As a bonus the car you hit will hit the car beside him and so forth knocking at least someone out of the track. One less to worry about coming back.
B will give you a single meaningless penalty while screwing up the pack with a very good chance to get ahead of them all. A will likely make you the victim of someone using B as a strategy and even if not, it has the chance of racking up multiple penalties just by rubbing around the corners a bit without anyone really getting in trouble.
Ergo, over the long run, the game awards bad behavior as a winning strategy. In 5 races today, every single race, B again and again. As long as the game doesn't make you give back positions gained after a bump it will not change.
There can be clean streaks as well where everyone is doing their best race clean. Yet what I have seen is that once it starts, things get worse first race after race with the same people getting put together again and again. Best to try a different daily race for a while when one is currently poisoned.