Your post is weird. Why would the amount of visitors to a country have anything to do with passports issued? The U.S. is less than 5% of the world's population. That's a hard limit on the amount of passports that can be issued.
The amount of visitors would be limited by the size of the tourism industry and regulations around entry visas. This is an unrelated metric.
That doesn’t mean it’s easier to enter the US than to leave. The US is a desirable place to live, so not many people leave while lots of people want to come here.
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.