Earlier quoted context omitted.
> Governments enforce borders to effectively secure their territory and people Only if by "secure" you mean prevent your population from leaving [1]. The whole origin of border control was to prevent people from leaving. The easy way to think about it is you can't leave a country without a passport but you can enter a country without a visa (exceptions apply). [1]: https://en.wikipedia.org/wiki/Passport#History
> Only if by "secure" you mean prevent your population from leaving Did you think about this statement for even 1 second? It should be clearly and immediately obvious that it is easier to leave places like the US than it is to enter it. This is obviously the case. You cannot with a straight face claim that actually it is easier to enter the US than leave. Clearly, leaving is easier.
It is in fact, 4x easier to enter the US than to leave. Passports are actually rare for a US citizen to have, you just live in a bubble.
[1]: https://www.trade.gov/sites/default/files/2021-03/Fact%20She... [2]: https://travel.state.gov/content/travel/en/about-us/reports-...