It's interesting that people try to explain this away with all kinds of retroactive in-universe technobabble. I mean, I enjoy Star Wars just as much as the next guy but it's abundantly clear that SW wasn't meant to be investigated at this level. It's space mythology, not hard science fiction. And that's fine! We can have fun asking things like "Why is the Outer Rim considered a backwater if it only takes a few hours to get from galactic center to the rim?" and we don't really have to stress about answers to those things as fans. Edit: Or we can if that's what fans enjoy doing, but it just isn't my thing and I think that's ok too