So you're point is that just because the illegal crossers will look for another avenue of illegal entry after they find the usual route too difficult or impossible after being fortified / secured then we should not even try it? That is the point of strategic fencing, to force them to only have very difficult avenues to attempt with low probability of success and/or high likelihood of capture during the attempted illegal crossing. Of course they will try something else, for every move there is a counter-move.
And it will not be trillions of dollars, not even REMOTELY close to that. Besides which, you can pick your poison for how much illegal aliens cost the United States in direct cost and indirect costs and it dwarfs the cost of a reasonable security system on the border.
Crime and illegal aliens in the U.S.
From 1980 to 1999, the number of illegal aliens in federal and state prisons grew from 9,000 to 68,000. Today, criminal aliens account for about 30% of the inmates in federal prisons and 15-25% in many local jails. Incarceration costs to the taxpayers were estimated by the Justice Department in 2002 to be $891 million for federal prison inmates and $624 million for inmates in state prisons.
That's just to house them at our expense after they committed some crime, just about 1.5 billion. The Israeli security fence system cost about 430 million for about 135 miles, just assuming you kept out only 50% of the would be convicts you could recoup your build out costs for building 6 135-mile sections of security systems in about 3.5 years and you have the benefit of having those prison beds available for some homegrown criminals who need a longer stay in the big house.
The Fiscal Cost of Unlawful Immigrants and Amnesty to the U.S. Taxpayer
In 2010, the average unlawful immigrant household received around $24,721 in government benefits and services while paying some $10,334 in taxes. This generated an average annual fiscal deficit (benefits received minus taxes paid) of around $14,387 per household. This cost had to be borne by U.S. taxpayers. Amnesty would provide unlawful households with access to over 80 means-tested welfare programs, Obamacare, Social Security, and Medicare. The fiscal deficit for each household would soar.
In 2011 there were about 320,000 apprehensions for illegally crossing into the USA, even if you only deterred 50% of them and assuming a them to be a head of household situation you would save on average per year in government benefit programs approximately 1.6 billion, just about enough to pay for the above six sections of 135-mile border security system and then every year you would have enough to maintain and man it.
Last point, why do we (being the United States of America) have to change because someone from a foreign country doesn't like an aspect of our society, that is a legal system that somehow 1,000,000 people managed to use legally in 2012 and they somehow can't? I guess some people don't have to file their income taxes because they find the form confusing and cumbersome... The burden is on the immigrant to use our system rather than the US bending for them.
No apologies for who we are or how we live, if they don't like it, figure it out somewhere else.