Not fastest, quickest.

These are all drag cars, and yes, in drag cars mechanized shifting is usually quicker and more reliable than human shifting.

Most of us here in the real world though, are not building professional or highly competitive amateur drag cars and instead want to drive our cars to work/school/shopping, take some occassional twisties, and maybe hit up an autocross or (heaven forbid) a drag strip. And for those things, most people enjoy shifting for themselves.