Why don't any RPGs let you enable two language packs at once?

I've seen some classic books printed in a bilingual format, left page is one language and right page is its translation.

That would be AWESOME to do to a game, why doesn't anyone do that? It wouldn't work for every game obviously, but, for any case where the text is scrollable, there's no reason you can't have the Spanish version on top and English below, or something like that. And for voice-heavy games, you could make them pause between each line, wait for you to read the captions, and press any key to continue unless you hit one specific key that asks them to say it again in the other language.

But for text-heavy ones like digital trading card games? The only thing stopping this would be needing to implement scrolling text cards everywhere.