Why Do We Need a Passport?

The passport was first roduced as a globally required travel document during world war one, just after henry ford introduced affordable automobiles. And to day that our passports are still pretty much the same way that they were a century ago,. i think there was a flaw in the way that the passport system was built. So why does it continue to work this way if none of us like it? Well, we tend to keep things in motion, right? And we don't like to make huge or big changes.