They all have weird 'riding' positions (prone, etc) so I guess it's a bit of a compromise between an super compact aerodynamic shape and what someone can actually put power out in.
Problem is most trackies are big or at least wider than roadie sprinter types and that's going to hamper your aerodynamics. You've also got to spend a shit load of time developing power in whatever position your vehicle requires.
They all have weird 'riding' positions (prone, etc) so I guess it's a bit of a compromise between an super compact aerodynamic shape and what someone can actually put power out in.