The item balance is so bad in this game. I think I could drop my controller down a flight of stairs during the race and have an equal chance of winning.
Its actually improved on Mario Kart 8 (WiiU) you can actually get green shells and bananas when in first. In MK8 you got coins 90% of the time.
Edit: All WRs will be heavies because they have a higher top speed. They are slower to accelerate, but on a WR run you wont screw up your line and need to change speeds much.