Uh, it's good to have both a physical barrier and clear fire zone to be able to observe and intercept with an optimal patrol manpower level.
Both Israel and East Germany seemed to have done the development work to get the best practices developed. Is it perfect? Heck no, but both a barrier array and patrols are required.
There are places where a fence is good, but if you read his statement he’s talking about the the great, unpopulated desert all across Texas (as we have here in Arizona) where there is nothing to stop them and a fence is useless. We need live troops with live ammunition patrolling those areas, a fence is useless there. Just ask the ranchers here in my state how much good that fence has done. Almost none! You put the fences close to civilization, that’s where they will help, but the wide open desert, nope need troops and enforcing the law.
Neither Israel nor German has miles of nothingness (reference the Brownsville to El Paso portion of the statement). Fences make sense near civilization, but ask Robert Kranze's widow how much the fence helped down by his place.