Even old analog CRT computer displays almost never had vertical refresh synchronized with the mains frequency. A CRT at 60Hz flickers very noticeably and irritatingly, never mind at 50Hz! 75Hz was widely seen as the minimum reasonable frequency for long-term usage, and high-end monitors would refresh at 90 or 100Hz.
Digital LCD displays would basically standardize at 60Hz because unlike with CRTs, flicker is not that big of a big problem, and getting LCDs to refresh even that quickly without ghosting or reduction in contrast was a fairly difficult engineering challenge. They're fundamentally DC semiconductor devices anyway, so mains frequency does not matter at all.