Ever been to the Texas/Mexico border? If you had, you would realize it's not just a line in the sand where you can conveniently build a fence. There's a major river that divides the 2 countries and people on both sides depend on having access for livestock and agricultural purposes. here are also areas where you would have to be a world-class rock climber to get across
Perry realizes this and even though fencing does work in urban/ high population areas (where it has been installed), allowing authorities to use natural and technological barriers where fencing is impractical is the logical way to proceed.
Throwing out half-truths without explaining what Perry actually believes is totally disingenuous.