Lower barriers to communication and the building of shared conceptual models of the domain will make a team much more effective.

An engineering team in the same timezone whose members have a similar general context for how they approach work will be able to do all of that more easily.

In my mind, that explains much of the difference.

Of course, there are fully-remote teams and companies that work hard to overcome some of those obstacles, but it seems to be non-trivial to do so successfully.