"Collaborated" is overdrawn. While a very significant portion actively collaborated, it's more accurate to say that the broader majority simply acquiesced the Occupation.

This is not to diminish moral responsibility (which I think is an essentially moot topic at this juncture). But rather to bring the focus back to how these regimes actually worked.

You didn't need to be an active collaborator. You just had to not actively resist, and keep your mouth shut (or at least keep your grumblings insubstantial and subdued).

Rather like in corporate environments today.