Say someone from Africa or South America. They can't simply save enough money, get on a plane, land at JFK and then after 10 years or whatever time become citizens. They would have to be persecuted in a terrible way before being granted asylum, have to marry a US citizen, find a company that would hire them.
I think that is very interesting given that this country was founded on immigrants just hoping on the boat and coming here, either to build a better life or because things got terribly bad where they were.
I personally went through the whole process and it is a fucking mess. I knew how to deal with it, because I dealt with bureaucracy in the old country. I can sense an annoyed low level clerk's power trip coming on before they notice it. Such individual need special treatment. You never want to fall into anyone's cross-hairs, it seems like they would destroy you just because they can.
Also know someone who works for immigration. It is quite a dysfunctional entity. Very inefficient. Lots of internal mistakes, unpaid interns do the job searching through databases and picking people out for violations & deportation. Next time you know someone was picked out -- chances are some kid thought their last name sounded funny and it caught their attention.