Trust Me

Why is trust so hard to earn yet so easy to lose? I don't really have a problem in this area but sometimes I wonder what would happen if I did. Honestly, I've never done anything that would constitute for my parents to stop trusting me. I tell them what I am up to, where I am, and who I am hanging out with. And I don't lie about it. Because I don't feel like I have to. They trust me, so they let me do basically whatever I want within reason. They are super reasonable about letting me stay out later than my already arranged curfew, all I have to do is ask. And I love it. But then, I also wonder what would happen if just once I did something wrong.
Would they flip out? Would one act against my better judgment cause them to lose their trust for me altogether? Would it depend on the size of the offense? What if it was something small like staying later where I was and not calling to make sure it was okay because I knew they were sleeping and wouldn't know the difference? Would they be really angry if they did find out? Even it I was truly just where I said I was only past when I was supposed to be home? I feel like that wouldn't be too big of a deal but they would still be disappointed in me.
But what if it was something huge? Like my friend and I took my car and went somewhere after they were asleep? What if they woke up and found my car and us gone? I'm pretty sure I would be in trouble for forever and they would never let me do anything ever again. Or at least for a very long time. They would probably take away privileges and anything else they could think of. But really, is that anywhere close to fair?
I understand that trust isn't one of those things that you build up and each time you do something wrong you lose a little but still have some. Nope, one thing and it is all gone. Or maybe that is just in the case of good kids. Kids that their parents aren't used to having to punish. I wonder if I was the kind of child who disobeyed them all the time and did stuff behind their backs all the time, if they would be more used to it, and I would be given more than one chance.
Luckily, I really don't have to do more than just ponder about this issue. I'm glad to have built up the trust with my parents that they let me do what I want. I cannot say how much I value that. I don't plan on blowing that kind of novelty any time soon, but I just can't help but think, what would happen if I did?