- it's too hard to build them in remote places
- people will just climb over or dig under them
- We've tried it already and it didn't work:
The Israeli Fence, like the current U.S. Fence has been built in and near HIGH POPULATION AREAS.
Look at the map of the Southern Israeli Fence. The Israelis did not waste money fencing off the Egyptian Sinai Desert from the Israeli Negev Desert.
Building a Fence in San Diego, CA is equivalent to building a Fence in the high population areas in Israel. Look at the Arab civilian in your photo taking a stroll on the road right next to the Fence and notice all the urban grafitti. Your photo is the Israeli equivalent of the existing San Diego Fence.
Building a Fence in the "middle of nowhere" areas of the Texas desert is equivalent to building a Fence in the "middle of nowhere" area of the Sinai Desert/Negev Desert border.
If the Israelis were not dumb enough to do that, why should the U.S. be dumb enough to do that?