Yes, this has come up many times before but here is a new twist.
I went to the post office today to mail a size 000 padded envelope.
Though it fit through the jig that they now have to determine that the thickness doesn't exceed 1/4 inch, the clerk told me that she had to charge me the rate for a parcel.
I asked why. She told me because she could feel that it has merchandise inside. I said what do you think padded envelopes are for.... fragile letters?

I wish these people knew their own postal regulations because I certainly don't