siriuskase's Journal: U.S. Is Dropping Effort to Track if Visitors Leave

Seems that matching exiting visitors with their entry visas would be relatively simple compared with all the other law enforcement related data keeping that goes on in this country. Everyone entering this country could receive a visa or some other document recording their entry. When they leave, they present the receipt and they are automatically eliminated as suspects of anything that happens while they are out of the country. If they have lost the paper, they waste time regenerating it (or faking it), hemm, there's an idea here, but it needs work. If you want to shorten the wait at the border, just collect the data and let the matching happen after the fact. It's better than not doing it at all. But this seems like mostly a techology problem. Are the algorithms for matcing entries and exits any more complicated than those matching people entering and exiting any other sort of database?