Why Do Some Kids With Bad Attitudes Get The Good Parents?

I’m 15 and I have strict Asian parents. I am the top of the grade, on a 3 year scholarship in my private school, I don’t do drugs or alcohol or sex nor do I go partying out all night, they rarely let me get out of the house and want me to study ALL the time. I even still have a bedtime curfew!
Whenever I want something (from something small like ice cream to iPhones and laptops), I have to work for it. They have this ideal life value that if you want something, you have to do something in return (like how I got my MacBook Pro – it was because I was ranked #1 in my grade that year). If I was even SLIGHTLY rude or disrespectful they would hit me and ground me. So I’m really respectful to my parents because of all the things they’ve done to me and I am responsible teenage girl with good behavior.
But I slept over at my friend’s house and I saw how disrespectful she was to her parents (she called them a$$holes and threw lots of tantrums). She has so much stuff (iPhones, clothes, money, etc.) and so much freedom. She can do whatever she wants and she gets whatever she wants without having to do anything.
I just think it’s not fair that I have strict parents while she has nice parents who never hit her or get angry with her and gives her everything she wants without working for it. Why do kids with bad attitudes get the good parents? I KNOW my parents have lots of money but they ONLY let me have stuff or give me money after I do something for them (from winning 1st place on a piano recital, to acing the English test) and my friend is sooo lucky!
She does NOTHING and gets everything. Why is it so unfair? Why can’t I have parents like her?
Why can’t my parents be more lenient like HER parents? SHE GOT AN IPAD JUST BECAUSE SHE GOT A 90 ON A TEST. If I got a 90 on a test, I’d get a lecture on why I should’ve gotten a 100!!!
It’s just so annoying and unfair!