Pretty sure quite a few of these, when seen from the other car's PoV would show you cutting him off at the last second, ignoring a huge run on you, squeezing them over, not giving them room, etc.!
No, not all of them, but part of racing AI is acknowledging the 'A' and allowing for the lack of 'I'!
And the race director's warning... what does it cost you? It's not like you are forced to do a penalty or a drive through, are you? In online, BOTH cars always get a warning for contact. That's how it is in iRacing, in GTS, in AC, pretty much all games are incapable of thorough stewarding and accurate blame assigning. So it's easier to just warn both players and get on with it...
Bottom line with the AI... Start from the back! Treat Lap 1 as a formation lap. Allow the AI to spread out a bit. But the main reason is to safely see from the rear where they tend to be a LOT quicker than you, and where they tend to be a lot slower. Then you can plan your way through the pack knowing in advance where you are likely to get mugged if you just sit there expecting them to be as slow as you, and where you can attack knowing they are slower than you.
Yes, racing humans is always more real, but best of luck putting a clean bunch together. Unless you can get a bunch together that all want to race at the same time as you, in the cars that you want to race, on the tracks you want to race, in the conditions you want to race in, PC2 basically sucks on consoles trying to get a clean casual room together. No room titles...
I'm pretty sure, given a choice between rooms titled 'Pro Clean or Kick', 'Rubbin's Racing!' and 'Drunk Oval Mayhem', you'd know which one was the good one. Best of luck without them..!