> at the local cram center.

If school covers the advanced topics, there wouldn't need any cram center. Case in point, my teacher gave me such challenging problems when I grew up, that tutoring schools were never necessary.

Also, not every tutoring school is about cramming. Instead, they are simply accelerating. The Art of Problem Solving is one of such schools. Another example would be those math camps, such as Math Path. Maths are fun, powerful, beautiful, and leads kids towards a promising future. American schools simply don't care enough about it.