I see the world as empirical evidence shows it, not as I wish it to be; and it shows many people in the world as rather simplistic, which should come as no surprise given the trite msg that resonated with them. Empiricism shouldn't be a revelation to someone who supposedly does engineering for a living.
Cultural identity is predominantly racial in the US; again no great surprise with much knowledge of its history. Also again quite understandable why some wish to hide that great embarrassment.
Trump comes from the development market of NY, where to be successful, it requires boldness, arrogance and stepping on toes. It is not a world that lends itself to nuance.
In recent years there have been a few high profile cases of criminals, deported numerous times, eventually coming back only to rape or kill someone. The liberal response always seems to express more concern for the race of the criminal than the fate of the victim. It's a complex multifaceted issue, but complex multifaced answers don't win elections. However, for people frustrated with the status quo, "all Mexicans are rapists" is about as bold as you can get.
In the face of the madness of amnesty, open borders and sanctuary cities, building a wall sounds reasonable.
In a world of increased attacks by Islamic fundamentalists, keeping them all out and extreme vetting sounds like a good plan. It's too complicated to explain to Americans that our foreign policy blunders are largely to blame for it.
Now, because I understand Trump's world, I also know he is not going to deliver on any of it.
You mentioned empirical evidence. That requires a controlled experiment with known measurable variables and quantifiable observable results.
While you are measuring shit in test tubes, Trump is setting off baking soda volcano simulations. Who is going to get more attention?