Hm. I would honestly step away from the "athletic" cut stuff then, to be honest. I think you'll find a lot of brands are opening to wider (or at least more tapered) cuts with bigger thighs. Worst case is you size up in the waist a bit, but I tend to find "athletic" cuts just accentuate your thighs vs fit them
gramicci, universal works, engineered garments, south2 west8, story mfg, frizmworks, vintage levis silvertabs, vintage nike acg, carhartt relaxed fit (sized up one), stan ray, carrier company work pants, evan kinori, de bonne facture, never cursed (mtm)
yea... i didn't want to limit my options so i just said whatever price range but still, I wasn't expecting this much $ (just for loose fitting pants, not like cashmere or smth)
stan ray, vintage silvertabs, carhartts, and jcrew should not be more than $100 at most, especially if you're open to doing just a little more work to find them on sale or used
the brands you previously listed, the amazons, levis, and targets of the world, have to go for a lowest common denominator of design, which for pants is still slim/skinny stuff
i used to think that way as well, but pants construction is actually pretty complicated. like you can't just add an inch of fabric to the thigh, you also have to consider how the seat is constructed so you don't flatten your customer's ass. it's the same reason you can't just buy pants in a larger waist size and have them tailor the waist down - you'll distort the seat and leg
meanwhile, when pant silhouettes are larger, fabric becomes more important in how it looks on your body. if you get wide pants in a flimsy, shitty fabric, they'll flap all over your legs in a really unattractive way as you walk. instead, you'd prefer to have a fabric with a bit more structure and heft to it so that it can hold its shape, but in general that also costs more
finally, the audience for bigger pants is still much smaller than the audience for slim pants, so you generally need to turn to slightly less well-known brands, which in turn means they're going to charge more than amazon or h&m (economies of scale yada yada yada)