WD-40 IS good for cleaning chains and other parts of the drivetrain but not great as a lube. My guess is the convenience of a quick spray and turn of the pedals

WD-40 IS good for cleaning chains and other parts of the drivetrain but not great as a lube. My guess is the convenience of a quick spray and turn of the pedals, then back out to rent outweighs what a bike mechanic would do for their own ride.