It's not that we don't acknowledge it, it's that we don't acknowledge it in our day-to-day lives because the difference is so small. Your talking femto-seconds or less between Northern and Southern California (due to acceleration and gravity and all that jazz).

If you're thinking time zones (which it seems like you are), those are artificial constructs designed to keep people in different parts of the world talking about time of day in the same terms (If I say it's 4pm, you have abpretty good idea that the sun is up and bright and there's yay-and-so-many hours until dusk, regardless of where I am).