On my first job with a uniform, I was required to wear black pants and a white pilot shirt. That's a pretty standard outfit, and a lot of companies just leave it to the pilot to obtain those articles of clothing. That first company didn't pay much, so I just wore whatever black pants kind of fit me at the second-hand store. Another company sent me to Mark's Work Wearhouse to buy a particular style. I think they wanted beige, but the style number was a men's style, so I spent half an hour or so trying to find the women's style that looked the most like the men's style, yet still fit me. I don't remember how that worked out. At a later company I actually did wear a men's style because I could get far better quality for the same price, and while the fit at the hips was not stellar, at least the legs were long enough, the pockets actually able to hold things, and they didn't have little cutesy buckles or offer tummy control or butt enhancement. Seriously, if you've never bought women's pants, you'd be amazed by what they claim to do. Stupid things had to be dry-cleaned though, and I'm pretty sure they were flammable.
In my job I have to crawl, literally crawl on my hands and knees, under aircraft. I have to lug things against my legs. I sometimes wipe oily hands on my pants (not my underwear, British readers). I sit on my butt for five or six hours at a time. I occasionally need to wear thermal underwear under my clothes. I want pants that are black, cotton, durable, and machine washable. They need to be comfortable, not too tight, but not so loose that you're going to see my underwear as I crawl under the plane. Not that I care all that much about that last one. I always figure if you're hard up enough that seeing a pilot's underwear is going to do it for you, then I can throw you that one for free.
After a while I settled on a style at Mark's Work Wearhouse. I would buy several pairs at a time, making them ship extra ones in from elsewhere to fulfill my order. A couple of years ago they stopped selling them. It wasn't just that they'd changed the style, they no longer sold a medium duty woman's work pant. They had the really heavy duty ones, not something I wanted to sit for hours wearing, and they had yoga pants and dress pants. So last year I carefully measured myself according to the instructions on the website, and ordered a few different styles from Dickies, all of which arrived big enough for two of me. I sent them back and ordered four more that fit me about as well as the ones from the second-hand store, but by this point the old ones that fit me well all had patches on them, so I kept and wore the ill-fitting ones. Now I have a collection of badly-fitting black pants some of which have holes in them.
Today I tried to buy more pants. I finally gave up when a link for women's work pants took me to a page where not only were all the pants too short for the actual models, but the models were all wearing high heels. I guess "working women" need work pants too. I'll have to go back to men's styles.