If sizes were updated to, say, 14Z, where Z is a common industry-wide body shape code, then it would be vastly simpler to find clothing that fits — and people who were a 22 before might now be a 16S, once the clothes are proportioned properly for their non-hourglass body.

The problem underlying this is that retailers do not want to advertise for more than one body shape, because that not only reduces their total profit (9x the models hired, 9x the designs to create, more complicated size ranges than simply blowing up a size 6 design with a photocopier), it also would force everyone in the industry to be revealed all at once as cheaping out on design and production, once the use of H for hourglass spread (since anyone who isn’t using a letter code is obviously Hourglass Only, based on the data). Corporations have multiple strong financial incentives not to do this, and their shareholders would revolt and fire any CEO who tried to reduced profits by incurring massive increases in design cost, product variants, model staffing, and retail/online logistics for the sake of “unattractive” non-hourglass women.

I think the EU’s “no more shredding clothes” initiative is going to have some very interesting ramifications over the next few years, as clothing manufacturers will have to choose between seeing people buy their unsold inventory at the local equivalent to Goodwill here in the U.S., or have to start selling clothing “made to order” with only a limited quantity kept in the store for try-on purposes. Apple, weirdly, already has a perfect logistics pipeline for exactly this approach; you can get an off-the-shelf option in stores, or you can customize it in eight to ten different ways and get something labeled “CTO” — Custom To Order. But that’s not a cheap logistics pipeline for a company that only has to set the copier inflation percentage based on your size choice today — the designs are for size 6 and then they blow it up by 140% for size 10 or whatever (yes, seriously, for real). So it may end up that once the clothing industry has to start making clothing on-demand, they will quickly expand into more options than the “print a ream of t-shirts and try to sell them in 3 months” profit-maxing approach that they’ve all coalesced into today.

That article mentions that custom tailoring can often cost more than the article itself.

We do. For men it's brands like Proper Cloth and for women it's Eshakti or creators on Etsy