When a driveshaft gets to a "certain length" or is required to handle a certain power level, they get lighter and more expensive, until you get past another point in length and power handling.

It is all about reducing shaft flex, whipping, harmonics and twist.

IOW, short low-power shafts do not have to worry about flex, whipping, harmonics or twist.

The more requirements... the more "high-tech" they become.