yea, there really is a big difference in the way people act in the S2 servers as opposed to the Demo servers. You will still find idiots here and there, but the racing is(usually)a lot cleaner and people don't just try to kick you because they feel like it. I went into a demo server just for laughs the other day, cause i haven't been in one in years. And i just have to say that it is a complete joke.
As for your racing situation, if they were behind you, then it is their responsiblity to pay attention to what you are doing. If you are not getting a blue flag, there is no reason, whatsoever, to let the person behind you pass. If they are faster than you, they have to wait until they get a clean area to pass. You do not have to cater to them.
The actual rule is, that the person behind does not have any control over the racing line, unless their front bumper is past your door. There are many people that follow that on the servers. But, like anywhere else, there are some people that think they own the entire track, don't care about anyone else in their way and because of that, cause accidents. Those are the kind of people that get kicked