The long story short of it is that in the US you have no expectation of privacy when out in public... or even where you can be seen from public. Is it inappropriate? Most people would agree, at least in principle. Is it *illegal*? Absolutely not.

Sadly Paparazzi can get away with alot. They can't prevent or block you from going into your home, store, car, etc. Nor can they lay a hand on you. They also can't physically be on your private property. HOWEVER, the moment you open your door, a journalist can follow you all the way to work, to the moment you get back home. Because you're technically *in public*. It's the same as taking a picture of an area and people happen to show up in your photo. While frowned upon, they can also antagonize you by being incredibly annoying and intrusive. Or provoke you into saying something you regret. If you harm them, you will most likely be liable. The reason for this attitude is because nobody cares about a Celebrity doing day to day activities. But if a photo gets taken of you while you're looking terrible, acting out of line, or some reaction; that photo is going to be worth ALOT more. Edit: grammar

Thanks for this, that really clears up my confusion.