What I've never understood about the thinking of companies who design and make products, is why they don't consider the obvious needs of their customers.
I mean, a woman doesn't need a fly built into their pants, but a man does.
Why is that hard to understand?
Why do companies persist in making sweat pants for men without a fly?
As far as that goes, what's wrong with putting in a back pocket?  Just because a man is wearing sweat pants, he still needs to carry a wallet.  Or at least, he should have a pocket to carry one in.
And then, at the risk of asking for too much, he also might want to blow his nose - even though he's wearing sweat pants - so maybe a second back pocket for a handkerchief would be nice.
One more thing.  While relaxing at home, sweat pants are comfortable, and you don't need a belt.  But even if you have an elastic waist, you still need a drawstring to assure that your pants don't slip down too low.
But when you go out to the store, you definitely need to put on a belt, to keep from totally embarrassing yourself by having your pants drag down to where you can't walk - but guess what?  No belt loops.
Who are they making these sweat pants for, with no fly, no back pockets, and no belt loops?