I learned Spanish working construction and landscaping with Mexicans as a teenager. Now days, most young people do not work thanks to their parents. It is normal to see Mexicans doing the lawn and pool work while the teenagers are sitting on the porch playing with their phone. A large part of society thinks their children are geniuses bound for college and common labor is beneath them.
I have spent the greater part of my life working in Latin America and being with Latinos. I will boldly state that I have a true "insider" opinion. Years ago, I worked with BORTAC in the El Paso and Tucson sectors during a support cycle. We had to have permission or a warrant to enter private properties on the border. It was always granted but often came with a "don't detain family X, they cross every year for work and then go back home." It was incredible how obvious it was if someone crossing was coming for work or crime and freebies.
Latinos often look at me as "one of them" and the ones that don't know me assume it is impossible that I speak or understand Spanish. I have constant access to some great "chisme" (gossip).

Years ago, Latinos would often approach me asking if I knew where they could find work without papers in the US. I would listen to conversations about guaranteed work with a friend or family member if they could find a way into the US. Now the conversations are primarily about what they can get free in the US (and other countries). I listened to a group of young people recently on a FaceTime call talking to a "prima" (cousin) in the US about what to say when the Border Patrol or Immigration catches them. Names and contacts for groups that will help them (mostly churches) and all their rights and freebies. Not the first time I have heard those conversations and believe me, it makes my blood boil. Mama often has Colombians asking if her Gringo husband will help them. She has been very clear telling them her Gringo is a very patriotic US citizen and military veteran and he does not support or condone illegal activities against his country. She also adds that she is a US citizen and military spouse and does not support illegal activities against the US either. But they still try. Don't even get me started on the "marriage for papers".
I don't have an answer, just thoughts and opinions. The "measured intelligence" for a VISA is an interesting thought. But most alleged geniuses are successful in their own country and have a VISA to the US. Many even have homes in the US and do the back and forth living between countries like we do. I do know we have a lot of hard working, productive members of society that are in the US illegally now. Why can't we have a program to "fast track" them to become US citizens. Also continue to fast track the parasites back to where they came from.
In general, the days of the hard working illegal immigrant that wants the American dream is over. Now, most of the new wave of illegals and immigrants want to live off the taxpayer or work enough to live off a small social security check in their native country. Economic status and intelligence level aside, if a person isn't a productive member of society in their own country, do we really think they will become "employee of the month" in the US or cure cancer?
Just a few thoughts as I enjoy a morning cocktail on my balcony in the Eje Cafetero.
Have a safe and pleasant weekend.