In a cable, the EGC size gets bigger in proportion to the other conductors getting bigger so 250.122(B) is satisfied.
I assume that is built into the listing standard for all cables.
In the case of SE cable (TYLZ in the white book) it says
Based upon tests which have been made involving the maximum heating
that can be produced, an uninsulated conductor employed in a service
cable assembly is considered to have the same current-carrying capacity as
the insulated conductors even though it may be smaller in size.
