system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: From the United States, you need visas to travel to some countries, but for others, passports will suffice. Why?

I understand that for some countries, like Cuba, the need for a visa is due to strained relations between countries. But what about for other countries, which we don't have bad relationships with? What's the determining factor?
gpt
It's not so much that you only need visas for countries with which the US has strained relations, it's that only countries on very good terms (and who do a lot of business) with one another allow visa free travel.

Countries treat visa restrictions as the norm and negotiate among themselves if they want to lower them. The US visa waiver program began in 1986 to help lower costs for tourists and people doing business.