All the San Diego fence did was reroute traffic to different areas. If a fence is built across the entire border the coyotes will revert to digging holes and tunnels, hence the need for electronic assistance.
The San Diego fence worked, as your own words prove. A fence works, it worked in East Berlin and it works in Israel and it will work here if we build it long enough. A fence that makes people travel another 700 miles to cross illegally is going to but down on crossings, if the fence is made the length of the border, and it could be, then they might dig, but digging is harder than simply driving across with a coyote and digging can be monitored easily with patrols and electonics, BUT patrols and electronics are not worth spit without the fence in place. Fence first and NEVER amnesty fence or not.
Digging a tunnel is a damned sight slower and more expensive than simply making a break across open territory. Detecting tunnel construction is simple and cheap. Nobody would dig a tunnel without the fence there.
Fences work. That's why boy George has one around the White House. That's why the G-8 built a seven-mile fence around their meeting.
It was built in a few weeks.
Sink the base of the fence 50 ft underground. It might not stop everyone - but it will stop a huge percentage. Then put cameras all along the US side to watch for burrowers. It is doable.
I'd be willing to bet if someone ran for President next year with the platform of building a wall across the entire southern border - they would win in a landslide.