Fair point. But: the way the modern meritocracy is motivated is that it is a fair system. It is the whole idea of the American dream. Work hard and you can go anywhere. Except some people have to work a lot harder and be a lot smarter.

It would be meritocracy if both kids had equal opportunity to earn those merits. If the ability to do so is itself gated, it's only meritocratic within the privileged group.

No, equality of opportunity is specifically not needed for a meritocracy. It wasn’t in the original book[1], it didn’t happen in the old Chinese examination system, and it sure doesn’t happen now.

Merits are measurements, and society adapts to make those measurements a target.

[1]: https://en.m.wikipedia.org/wiki/The_Rise_of_the_Meritocracy

Oh, but this is not how meritocracy is ever viewed in a liberal democracy. Equality of opportunity is the defence on an unequal society.

For the inequality of outcome to be fair and just, there has to be at least some kind equality of opportunity in a meritocratic society.