It’s difficult to maintain basic features in a popular calendar, at least according to the ms exchange team blog:
> calendaring is particularly tricky. Why’s that? Well, consider time zones for a start – a meeting you set up isn’t necessarily in the same time as it is for me, and then you also invited people, from a whole bunch of other time zones (did you know some time zones are 30 mins off, not a full hour?) (…)
> calendaring is particularly tricky. Why’s that? Well, consider time zones for a start – a meeting you set up isn’t necessarily in the same time as it is for me, and then you also invited people, from a whole bunch of other time zones (did you know some time zones are 30 mins off, not a full hour?) (…)
https://techcommunity.microsoft.com/blog/exchange/calendarin...
Then there is the “falsehoods programmers believe about time” list: https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b... , with some counter examples: http://www.creativedeletion.com/2015/01/28/falsehoods-progra...