I'm not sure it can be quantified in terms of "how much," but there's certainly a greater-than-zero amount. Even if the book had a clear and unambiguous list, we'd just as easily be raising this point with regard to "new players who can't/shouldn't be expected to memorize everything." By that token, if a player scribbled "gloves" on their character sheet despite them not being in the PHB, I think most of us would accept that their character is wearing them.
Then, as outlined previously, you run into an issue where I think the DM needs to be the one to adjudicate something, even if it's an infringement on the player's interpretation of their PC. I'm relatively confident that there was medieval footwear that didn't use laces, for instance; with nothing else to go on, who decides whether or not that's what the PC's footwear has?