I would imagine that the method of security tagging that is common in most libraries these days is equally an issue as is the barcoding. In our university library everything movable is tagged with the exception of the staff and students, as yet. ;-)
So it is difficult to remove anything out of the library without the alarms sounding. The barcoding is primarily used to determine who has got what when they leave the building and then at that time the tags are neutralised.