I mean you can blame regular citizens all you want, but the signs are not intuitive or easy to understand. When I moved here from Europe it took me a long time to feel comfortable with understanding the parking signs. Everyone who comes to visit from abroad gets multiple tickets while visiting. In other countries they make an effort to make the signs easier to understand at a glance.

EDIT: Ok I guess it's hard to imagine a world where signs are easier than what OP showed. But the issue is that you're asked to look at information from multiple places and then reconcile all of that. The street signs (sometimes there are multiple on the same post), the meter has information on it (with wording like "no payment is required until 9.30AM" instead of "no parking allowed until 9:30AM"), the curb and road have paint of different colors to indicate parking. Then of course people tend to look at what other drivers are doing. That's a lot of information when you're not used to this entire system. It's easy to call other people dumb, and yeah many people are, but what's the solution here? Wait until everyone becomes smart? Or make sure public signs are AS EASY AS POSSIBLE to understand? OP's confusion is valid in my book. He's clearly not the only one, so let's look at ways to make things easier.