There is only 1 item that is first place specific and that is the blue shell, everything else will happen to at least the 3 or more racers behind you if not all of them (bar the one who sent it)
If you are a good enough driver a single blue shell should not be enough to knock you from 1st to last as you would have been too far ahead of the rest by lap 3.
Yes at times you can be unlucky, like getting a blue shell as you are flying over a lava pit or something, but this is rare and it is not so much of a chore to do the race again should you fail to come in first.
Playing through single player myself there were only 5 cups I had to repeat to get a gold, and now I am better it is rare I don't finish with the full 60 points in any CPU GP.
Perhaps some people are not quite as good or are getting used to the Wii Wheel, but unless you are terrible you won't be repeating a cup many times at all to get gold.
Why does everyone want this game to be made easier or harder or both? Yes there is an element of luck going by the timings of the major items (blue shell/lightning at the wrong time can mean doom, but that is part of the game and does not happen any more than in Double Dash as far as I can tell) but if there was no element of luck then Rol would never have lost a race, and the newer players would never get any glory because they would always be last.