[“They count on this as part of the budget,” said Louis Weiss, a former supervisor of the DEA group assigned to Hartsfield-Jackson Atlanta International Airport. “Basically, you’ve got to feed the monster.”
In most cases, records show the agents gave the suspected couriers a receipt for the cash — sometimes totaling $50,000 or more, stuffed into suitcases or socks — and sent them on their way without ever charging them with a crime.]
Just like most things (everything gov't), it's all about the money.
I think they have an electronic way of scanning for large amounts of bills.