I think it also has to do with seeming unrelated societal shifts. For example, confirming that someone is going to take out the trash is important, at least in my neighborhood - we'd get a hefty fine if we left out a full can anytime other than between 6pm the day before trash pickup - 6pm the day of trash pickup. So if no one takes out the trash, we pretty much have to live with a week's worth of old trash in our kitchen.
In the days before cellphones, this would have either been discussed the night before at the dinner table, or there would have been an established chore list/timetable. But as society has shifted, family dinners have become rare, and the idea of giving your offspring a list of established chores sometimes appals parents (I have actually had other parents say to me that I am abusing my children, treating them like servants, because they have set chores; and if I can't do everything myself, I need to hire a maid). So when can this be discussed, if one does not call a parent at work?
If I need to meet up with someone who does not use cellphones (they are usually older people), we discuss that we'll meet at x at 3:00, and then we meet there. If I need to meet up with someone that DOES use a cellphone, it's not uncommon for them to call or text and say "I decided to stop somewhere- let's meet up at 4 instead" or "I'm hungry, let's meet at y instead." I don't know if this is a shift (where rudeness in this fashion has become acceptable) or if the timeframe for this to be acceptable has become much smaller due to cellphones giving people the ability to notify people of changes like this at the last minute (because before cellphones it wouldn't be too rude to call, say, the day before and say let's meet at y instead so we can eat")...