I have shopped enough with my wife to know what a nightmare this is.
Shopping for clothes and the variation of sizes...
That is especially true for jeans. What’s a size 12 in one store may be a size 10 or less in another. Now we have photo proof thanks to an 18 year old named Chloe Martin. She went jeans shopping and put six different pairs of jeans laid out on top of each other. Here's the pic
The difference is amazing. Some pants are inches smaller but they are all labeled size 12.
She also points out "vanity sizing," which is why a size 8 dress today is about the same as a size 16 dress in 1958. Hmmm.