Tunnels, ladders, drones - even float a boat around the wall....I see lots of South Americans taking cruises to Canada in the near future. No wall up there.
But you are right, you cannot stop every determined actor trying to infiltrate the country. Sending the jobs south of the border didn't work, so now what?
I believe the real issue is not so much the PRESENCE of "illegal immigrants" as it is their soaking up public resources while many of our native countrymen, service personnel, etc., wallow in poverty. The rape, murder, and mayhem aspect is just used by the alternative facts agencies and politicos to sensationalize and propagandize the subject.
Besides, if we were one worldwide nation, who would all the intelligence agencies spy on? Yep, the people.
We will never be one world. Didn't work for the Romans, won't work for any nation. Even the "United Nations" can't agree on sh!t. Can you imagine the volunteered abdication of kings, queens, dictators and the resignations of national presidents? The willing disassembling of whole governments, military forces, arms and munitions factories?
Me neither.