Indeed, it's strange looking in from the outside that they consider the country to be so precious in this fashion. I would not go if I were paid a large amount of money to do so, and I have been offered exactly that numerous times, so that's not just hyperbole either.
The US is not a shining city on the hill, it is a slowly sinking empire with walls made of disjointed, often incoherent words, that even the people charged with enforcing the measures extrapolated therein don't actually understand letalone hope to reasonably enforce.
But most of those immigrants are sneaking into or being smuggled into the country, as opposed to trying to cheat their way through immigration and border security. The former involves a backpacking trek through the desert whereas the latter involves years if not decades of expensive, arduous bureaucracy.
Around 40% of illegal immigrants in US had valid visa when they initially entered the country but overstayed. Also significant number of people came into US on tourist visa but then exploited the system to change status through genuine or fake marriage to USC, asylum, study, etc.
Technically if you get married or plan to get married you are supposed to leave the country and get either fiancee visa or immigrant visa by applying at the consulate abroad. Many (most) people ignore this rule because there is no penalty and many immigration violation (like visa overstay) are waived if you get married to US citizen and change status inside US. You can also appeal immigration decisions. On the other hand if you leave the country with visa overstay, you can be banned for three or ten years from getting any type of visa (even marriage-based one) and the right to appeal is pretty much non-existent.
Overall immigration law is illogical mess with conflicting rules that can often be exploited if you have money and a good lawyer. But even with a good lawyer the system can fuck you over as in the case of that woman.
They may not have a choice. I can perfectly well see why they erect barriers and put large obstacles in front of people trying to cross their borders. The problem is rather that startups should not demand that you physically move over there. I have had the case several times and I had to refuse the project. Moving over there, is unpractical. Why not collaborate remotely with people around the world? Do people really need to sit next to you in order to work with them?
Citation needed.
Seriously, Americans need to stop perceiving foreigners as unwashed masses, most of whom are seeking to abuse the system.