They have an entire museum dedicated to show the different ways people would get over, under and frequently through the wall. It will absolutely blow your mind.
If there were ten thousand illegal immigrants in the US instead of ten million, it wouldn't have the deleterious effects on agricultural wages (and consequently job prospects for low-skilled US workers) that it has.
They took your job? Seriously? :-)
For the future, don't worry ... agriculture is exactly the kind of work that will be done by robots.
If it is not already, that's just because your unions are out of control, which made countries like Japan take the leadership in the robotics industry.