Citizen tourism is not a real concern; good grief why do people care about fringe issues that impacts no one instead of concentration of corporate power, consolidation of wealth, and decreasing rights for citizens?
Because the people in power don't believe those last things are problems, so they distract us with the former things which actually aren't problems that they present as problems.
The best I can tell, 7-9% of US births are to non-US citizen parents. Maybe you could clarify what exactly you mean by “citizen tourism?”