The instigators of this little shindig forget a major truth: "Proper prior planning prevents piss poor performance."
Along with, "Play stupid games, win stupid prizes."
Their whole point was to inconvenience the public, to make a demonstration of how "essential" illegal immigrants are to the American way of life. What they either forgot or chose to overlook was that inconveniencing the public necessarily also inconvenienced the employers for whom the demonstrating [former] workers [formerly] worked. But ... people who run companies are in business to make money, so if the workers don't show up, they (the employers) will find another way to get the work done, or hire someone else to do it.
Just think of the irony -- all these formerly-employed immigrants can now stand around outside their former places of work and look at Americans doing the work that the illegal aliens didn't want to do.