If you are a person who is only willing to do just enough to get by,

(A) how does that prepare for your more difficult, higher level tasks which you aspire to?

(B) why would anyone want to hire or pay someone's who's approach is to do the absolute minimum level of achievement or competence to get by?

In a competitive business environment, companies that have the people who do the best work for the companies, who, in turn, supplies the best products for their customers are the ones who win the business, make money, and stay in business.  They aren't going to be interested in someone who scrapes by.  How do they measure that without knowing you, very well?  They look at your grades, etc.  If your history at the high school level is one of mediocrity, they're more likely to say "high school isn't that hard, and this person barely made it" vs. "this person is the genius/superstar that will vault us to excellence, and they've been saving it all up for our challenge."

As someone who has always been very gifted and brilliant, but not effort-focused, and who has often been deemed as not fulfilling great potential, I can say your explanation sounds more like a justification for not trying, more than a reason.

I instilled the exact opposite attitude in my own kids because it burned me badly throughout life.  I've had to scrape and toil all through my adult life, while those who were definitely less bright or creative than me, but much more willing to work, have been able to enjoy much nicer and more comfortable lives.  

I like who I am, but you're setting yourself up for a lot of drudge and grind that is unnecessary.  It doesn't end, when you're on your own, because that's all you have. It's not like when you're in high school and your parents provide that for you.

Your parents simply know better than you, on this topic.  Regardless, I've framed it in a way that removes the parents and their expectations from the equation.  It's self-destructive on a personal level.

> I'll be 17 soon, and I believe I'm being treated like a young child. How can I get them to treat me like the age I am? 

Excuse-making to justify lazy, self-defeating behavior is not adult behavior.  Harsh as that is, you need to behave responsibly to earn that respect and treatment.  You're not demonstrating it on this issue.