Unequal public education, yet equal standadized testing??? Hello! THERE'S A

[Corey B]

PROBLEM HERE!? It has always been very well known that some grade schools, and sometimes even entire districts, are failing to prepare their students for the future. For example, one student can attend thriving schools; therefore, be offered an excellent education. The next student can attend mediocre schools and be offered a mediocre education. Everyone knows, this is a scenario that happens everyday.
Nonetheless, when it's time for these two students to take the SAT/ACT, obviously the student who was offered the better education has an advantage, as he/she is more familiar with the material.
The point I'm trying to make is the playing field is not even. How can we have unequal access to a grade school education, yet the standardized testing be the same????
I am NOT saying let's curve the testing to make scores even. I am saying there will never be equality until equal education is offered. Why do mediocre schools exist in America?
Give me your thoughts. Is this to much to ask? Too little?