Ye, I figured this would be some sort of a industry practice. But as you said, there is a sensible way of integrating these things into a service. When I choose domestic destinations, they don't need to show me this huge list of meal options (which anyway won't be available on domestic flights).

And in case of a registered user (or a frequent flier) they already know my meal choice, so they can show that on top (or may be even as default), instead of showing popular meal choices.