“Some of the detection technology employed by the CBSA includes ion mobility spectrometry, x-rays and Narcotic Identification Kits. These tools, in combination with the officer’s knowledge, experience, training, enable successful enforcement actions.”
In other words, they found it by pure luck.
I like to imagine they were just found in random shoes over the day that people lost/forgot. Someone gets to Vegas and goes ah, fuck, I lost my coke shoe!