The bottles have a neck label that also covers the cap and is torn when opened. The mark itself is halfway across the neck label and halfway across the glass container. Once that neck label is torn, the mark remaining on the glass bottle makes it noticeable to the trained eye if the bottle is reused, which commonly occurs in counterfeiting. Matching a code to preprinted material can be done with a laser. That limitation does not exist with a laser.
Lasers can put sequential or similar numbers on packages using the same font.
Casually looking at one of these products, one may not notice that there is a lot number or identification that is particular to that package. Again, unauthorized duplication would be difficult. There are two schools of thought pertaining to traceability and coding. One is to make the code very large and very visible. In doing so, the difficulty to remove or change becomes obvious.