Because the US will self destruct if it does. Businesses won’t get raw materials for their products, or labour.

I remember one year they threatened to close the border because of migrants. But then backed off with just a verbal commitment given from Mexico. I can just imagine the perfect phone call trump got.

And that’s just Mexico alone. Trump had to back off on the Chinese trade war because businesses couldn’t handle the pain even with gov reimbursement.

Imagine what would happen if they sanctioned both Mexico and China?