Criminals are using cloned trucks to bypass security:

Savvy criminals are using some of the country's most credible logos, including FedEx, Wal-Mart, DirecTV and the U.S. Border Patrol, to create fake trucks to smuggle drugs, money and illegal aliens across the border, according to a report by the Florida Department of Law Enforcement.

[...]

In August 2006, the Texas Department of Public Safety, on a routine traffic stop, found 3,058 pounds of marijuana and 204 kilograms of cocaine in a "cloned" Wal-Mart semi-trailer, driven by a man wearing a Wal-Mart uniform.

In another case, a truck painted with DirecTV and other markings was pulled over in a routine traffic stop in Mississippi and discovered to be carrying 786 pounds of cocaine.

This is the same problem as fake uniforms, and the more general problem of fake credentials. It's very hard to solve.