Clothing sizes are somewhat useless. They should help find a fitting piece of cloth. Yet most times they are not enough or are straight-up misleading.
There are many problems with the current state of clothing sizes. Here are some in no particular order.
There Is No Standard
At least, I am not aware of one. And it's not even worth it for me to look it up. A company can decide for itself, how a size fits. And even then it's not a guarantee.
I once bought two pairs of pants from the same company, having the same size. One of them was a little bit too large, while the other was a little bit too small. Both were Sweatpants, so a difference like that shouldn't happen.
Companies Are Confused
Some companies don't even know what size to give their clothes. You might come across a piece being size X. But when you look in the description it says it fits like size Y.
What are they trying to achieve with that?
Current Indicators Aren’t Enough
Letters like S, M, and L are trying to help with orientation. But in the end, you still have to look up the relevant sizes in the size guide.
Jeans usually use their width and length as their size instead of letters. While this is still not enough, it is a step in the right direction.
Human bodies are very diverse and differ from individual to individual. So clothing sizes should respect that fact and have their fittings as their sizes. They should not have worthless letters.