If the pie manufacturer uses Grade B eggs, and a lot of them do...
...the yolks are small and low in iron, so a kind of pale yellow, a suitable color to paint a bedroom, but nothing like a lemon custard ought to be.
Grade A Large or Extra Large eggs give a lemon custard that sunny color. The lemon is for flavor, not color. Extra Large eggs leave you with more whites for the meringue, too, which, let me guess, looked like a curly tan mountain.