they get a pretty big lead at the start, and the tracks are difficult enough (citta nuova) that it's hard to claw it back. especially since the ai now uses all weapons. I probably overstated before too, their weapon usage is often evil, getting you just before a corner so that you're likely to hit the wall on the inside as well as taking their damage. they do not play like humans though. doesn't seem to be any intentional ramming for example.
and in the timetrials the times are pretty damned good, so it's not easy to get golds right away there either.