You're wrong about the calander too, they adjust that because of disagreements over when to begin the counts from, no-one actually disagrees about what time of day or night it may be. The only thing you might be able to complain about there is - why pick Greenwich as the zero-marker? Probably partly because Britian had an Empire so they would have wanted to know what time it was over in Oz or Canada or whatever, also because the Pacific having all those islands in a lot of sea makes it a bit easier to put the changeover bit out that way.