Foa a nice discussion about probabilities, we actually have the data to discuss. I am still missing the in-game data of MKW, but we can use jdaster64's data for now:
Mario Kart 8
Mario Kart 7
Mario Kart Wii
Mario Kart Wii has actually a maximum Blue Shell probability of 7.5% in both GP and Versus Races, while the Lightning has a probability of
22.5% in local races and
20% in online races (but in GPs CPU players have a probability of 17.5%...).
Mario Kart 7 has a maximum Blue Shell probability of 10% in GP races and 15% in Versus Races (CPU players are always stuck to 10%), while the Lightning's maximum probability is
25% in Grand Prix races (!) and 15% in Versus Races (the CPU players have 12.5% and 10% respectively).
Mario Kart 8 has a maximum Blue Shell probability of 2.5% in GP races and Versus Races (CPU players have 2% and 2.5% respectively), you have to go into Frantic Mode to have a maximum probability of a whopping
5%; the Lightning has a 7.5% maximum probability in GP races and 5% maximum probability in Versus Races, with Frantic Mode not changing the maximum probability (the CPU players have a maximum probability of 2.5% in Versus Races and
1.5% in Grand Prix races). When you are more than 26000 distance units behind the 1st you don't receive any Lightning, possibly to avoid that phenomenon known in MKW as bagging (going backward in team races to be the last and get the Lightning).
I would really like to see MKDS and MK: DD numbers now to see how much we had to wait before having MK8's numbers for the Blue Shells and Lightnings...