We don't ask, because we've learned from both direct & indirect experience that we won't get it (and may be punished for asking). We're good at making something from nothing, we just do it and others expect us to; thus making most needs seem a matter of wants, and wants being looked down on as waste, we learn there is little point in asking for more.

You are a good manager, sensitive to how a little money spent on a good chair can make a great difference. Alas, you are not the only one subordinates are exposed to, and takes little for others to undo the good you did.