in lapped races, people who get lapped should be merged into a world with only those who are on the same lap as them as it's pretty annoying when you're in first and someone is driving a bit stupidly and blocks you.
i think the races should start how they do now, but as soon as you enter lap 2, you will be merged into a lap 2 world, so those in lap 1 can't bother you any more and when you go in lap 3, you will be merged into lap 3 world and so on.
if the race has 4 cars per world, when you enter lap 2, you won't be merged with everyone, you will only be merged with those in your group (once they have entered lap 2 that is).
i don't really think you can say "well it's just racing that is what you have to deal with sometimes" because this is samp and chances are, the people you lap aren't regulars and will try to block you deliberately.