Considering the advice to add 3-5" to the band size, which hasn’t been necessary for decades (wiki actually says it wasn’t even necessary when the convention arose in the 30s), is still given out regularly, it’s no surprise that a lot of women are wearing the wrong bra size. I’m tempted to try on a 38A to see if it fits better than the 34C I wear by the way you’re actually supposed to measure (each 1" different between bust and underbust is a cup size). I doubt it.
As for clothes, I’ve given up expecting the same sizes across brands, but why the hell can’t the same company make their sizes consistent? I’m not even talking about different styles either: I bought two pairs of Rider Casuals last month, and the cream color ones in a size six fit exactly the same as the pair in black in size eight. WTF?