Apples to oranges. Where there is a will, there is a way.
http://www.time.com/time/photogallery/0,29307,1895418_1877457,00.html
From 2009 - Over 100 tunnels found back then:
http://www.cnn.com/2009/CRIME/04/16/creative.drug.smugglers/
Build a fence, they'll just use a bigger catapult:
http://www.prweb.com/releases/drug/trafficking/prweb8145166.htm