Driving pet peeves

When I'm out driving I'm a pretty calm person however there are some things that people do that can get annoying and I have no idea why they do it. For example I don't like when people are changing lanes every 2 seconds just to get somewhere faster then they end up at the front of the line at a red light then when the light turns green they drive pretty slow. What's the point of driving like your in a hurry if your not committed to it. If I were to actually be in a hurry then I wouldn't take off slowly from red lights or get stuck behind a car. Another example is people that drive fast thru an alley(there's one behind my house) especially when it's during a time when kids are playing and by fast I mean 30mph+. Then when they park and I drive by them at 7mph they get mad and say I'm going too fast and they have a kid to protect. The irony is incredibly delicious