I played about 30 mins with mates and they like rather play mario kart
Well I think that sums up why your friends can't compete in higher difficulties and everything else we've discussed surrounding your friends in the game.
but i just feel the drifting in mk64 better and overall handling of a vechile that bit better.
I hope you realize the amount of combinations there are to modify pretty much everything about your vehicle in Sonic Transformed. And then there's the fact that any type of controls will become default after a while.
The planes and boats aswell, they deliberately made the controls for boats and planes very different. But they're both manageable, that's where you see who is willing to get better at a game and who just wants everything to be easy from the get-go.