What does US Customs & Border Protection expect to find by searching?
The battery compartments of electronics have been used in the past for bombs. A Pan AM flight was blown out of the air over Scotland, killing all aboard, by a Libyan who had a bomb in his laptop. Other bombs have been found in telephones. At altitude a very small explosion can decompress an airplane and if placed in the right position, affect the controls. At the border they are also looking for drugs or things of value, like gems that were not declared.