The young men who are at the age where young men start wanting a motorcycle have yet to learn how to drive a manual shift car.
Being able to operate a clutch and shifter is a very fundamental part of operating the vast majority of motorcycles.
Besides,....everybody under 45 is broke.
Back a year or so ago I heard an upper 20's guy say the $1400 c-19 check was the most money he had ever had. Not much later heard another say basically the same thing.