Why are the front parts of trouser-legs narrower than the back parts?

So that the tops of the back part can accommodate our asses?

(Great to see you, @wildflower)!

@janbb, I think you’re correct. For most people, the muscle mass of their thigh is at the back of their leg, and not the front.

The back part of out legs (calves) is bigger!

Cause you got dat junk in da trunk, homie.

To cut down on wind resistance.

hmm….I can follow the logic of accommodating bums, thighs and calves – but that raises the question of why the cut-off for front/back is further to the front, leaving more mass in the back…
....this is why I shouldn’t iron!