Can't tell if this is sarcasm (I've been on the internet too much today sorry) but just in case the Greek μ (mu) stands for "micro" since 'm' is already used for "milli"
yeah, i get that, but many people just use u because its more accessible (ascii and qwerty compatible), similar to writing μBittorrent as uBittorrent. imo i dont think its too big of a deal if it doesnt match the word micro, since μ is already a bit of a stretch. this is just my opinion, im not advocating for a SI reform or anything :)
μ is not a stretch at all, it's literally the first character of the word micro. (Mu, iota, kappa, rho, omega). Similar to how other scientific words are derived from their original language.
It doesn't matter, most people will understand you if you write um instead of μm, because it isn't ambiguous.