People capable of Einstein’s genious are born daily. There’s two major reasons we don’t her about them.

First, (your suggestion) we have to live under capitalism. Opportunity is distributed poorly and depends directly on circumstance and luck. So most people who could be another Einstein end up working at a service job to survive.

Second, the sciences have grown so much that these works are now the leaves in the canopy of a dense forest. Sure, you can see the trees, you can see the leaves, but every single tree is a different subject, every branch a new revelation, every ring built upon the previous, every leaf subdivided into thousands of little bits, and even the cells with component parts. Once you start learning about a subject you start to see just how complex something as simple as the tree really is. So just like you don’t see every individual leaf, you don’t hear about these people.

Bonus: science isn’t the only place for genius, there’s tons of absolute geniuses working as artists, and that’s a good thing.