system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: how does a country's passport "strength" work? How does a country become visa-free for another country?

It is stated in Henley passport index, that the top three countries are  Japan (1st) , Germany and Singapore (both ranking 2nd), what gives a country passport the strength to be visa-free in other countries?
gpt
The governments of Japan, Germany and Singapore (using your example) went to a BUNCH of other countries (USA, Argentina, Egypt for example) and said, hey, can you let our citizens visit your country without having to get a visa beforehand? Those countries governments looked at Japan, etc and thought "hmm, their citizens make good money, generally obey the laws, like to spend money here as tourists and arent likely to overstay...". Sure, you can have visa on arrival.  Rinse and repeat for like 150 different countries = a lot of countries they can travel to with a visa on arrival = Strong passport.

Now, lets say the government of Elbonia went to a bunch of other countries and asked the same thing. Now the USA, Argentina and Egypt are thinking "Elbonians earn like $100/month, dont follow the rules anywhere they go, dont have any money to spend and will probably overstay in our country to work and earn more than $100/month". Uh, no; sorry Elbonia. You guys want to come visit us, you need to apply in person at one of our embassies beforehand, pay a fee and prove to us that you have enough money to get back to Elbonia and won't overstay.  Rinse and repeat for like 150 different countries = a lot of countries they CANT travel to without having to get a visa at an embassy first = Weak passport.