Product discovery in general is a mess. It's not a particularly high bar you have to pass in order to build something that's better than your average online storefront when it comes to product search and comparison.
Jeans are probably top 3 worst products to shop for.
Mens sizes are literal measurements in inches, ostensibly. However when you look at the sizing chart on brand websites you realize they all have varying levels of vanity sizing - across brands, across fits within a brand, and across years within a fit.
Then you have all the confusing nomenclature for fits - skinny, slim, straight, classic, standard, relaxed, boot cut, baggy, flare, athletic, etc.. And then hybrid ones like "slim straight" or other nonsense. Finally, some brands offer different inseams/lenghts for a given waist, while others have fixed ones per waist size so you have to get them tailored after, etc.
The shopping experience for me in jeans is to trying multiple brands/fits/sizes every 5+ years, and then keep buying that exact model until it is no long available, then reset.
Also if you've ever done a deeper analysis of Lucky jeans, the same exact model is wildly different depending on where it got produced. Different material composition, fit, flexibility/softness (due to the difference in materials), different country it was produced in (and IIRC, it's not even consistent. Mexico is not always 100% cotton for example. There was no discernible pattern)
I try to find products I like and then buy a bunch of them (in case they stop making them, etc) and I wound up making a spreadsheet once after becoming frustrated with the inability to trust the same "model number" means the same thing there.