Vanity sizing

The size on the tag is a starting point for what to try on--this is what women have dealt with for years. I was recently shocked to purchase a pair of shoes in a size 9. I haven't worn size 9 shoes since I was in high school. I currently wear 3 different numbered sizes of clothes. I generally consider the largest size the "true" size. How can this be? It is known as vanity sizing.

Men are subject to vanity sizing too. It never occurred to me since men's pants are sized in inches. I bought a pair of 5.11 pants and they were sized in inches, whether women's or men's. I think I tried on 5 pairs before I got down to my size. It was the first time I bought pants sized in inches in many years. When waist size is considered an indicator of health issues, should clothing manufacturers be able to mislabel pant sizes?