Under “settings” (available from WPAdmin, and probably other menus as well) I get to select my preferred date/time format. It seems to be respected most places by not everywhere. It is respected on the WPAdmin menu for example.
On the stats page for example, time defaults to AM/PM, and not the 24-hour clock I prefer.
That doesn’t even come close to the annoying nature of menus like “Comments” which default to the completely useless (3-days ago, 1 Week Ago, whatever)
I’m sure you’re amazed at how clever you are to program the date arithmetic functions of you database of choice, or the functions packaged in the library code you’re using. But an actual date and time would be more useful.