As I said before, I really doubt there is any scripting in the AI behaviour. I'll try to explain why.
AI makes decisions on what control input to make depending on it's own status and what's around it, nothing random. Consider taking the human player out completely and at the start of a race or test the conditions are always exactly the same so every decision made by each AI player will always be the same no matter how many times you restart so races will always play out exactly the same way.
Now throw in a human player, the human won't ever make exactly the same moves from one race to the next but the cars ahead won't be affected until he catches up with them or if he interferes with a car in front that then in turn interferes with another in front of it, chaos theory. So until the human player causes interference directly or indirectly the AI race going on in front will always play out the same.
Have you tried this out? I mean, my initial thought is to agree with you, but I've not tested it.
My experiences with the AI are a bit mixed. I absolutely hate the 1-lap magic ********. I understand the contact "rules" and do my best to abide by them, but when you need to lap 3-ish seconds faster than the AI (as you do on the Elise Top Gear challenge) there's obviously going to be problems.
In order to overtake as many as possible at each corner, you have to brake
deep into the corner. This is accentuated by the fact that the AI brake early (just) and pootle into the corner, but always seem to have perfect traction (although their exit line might not be ideal), so there's really little other option. So what happens is you're much faster on the way into the corner, but then have to slow the car right down to get it turned around ready to catapult out of the corner in a straight line, so as to get the drag on the AI again down the next straight.
The extra speed into the corners means you're liable to hit the AI as they take their (legitimate) line into the corner, especially given you're almost always coming at them from a
long way back. Then, as you rein her in to take a stab at the next straight, you're now going much slower than the AI is in the corner, so they're liable to hit you (almost certainly as payback

) compounded by the necessity to take an "unusual" line in the corner.
This isn't poor collision management, it's poor game design. The one-lap magic from GT4 (or was it GT4 Prologue?) where you only needed to overtake three cars, who drive at a consistent and decent pace, were much more appropriate. Maybe they tried to take the concept and "turn it up to eleven", but they ruined the feel, and sense of accomplishment, in my opinion.