The guardrails you refer to are more like those fabric bands used in movie theaters to direct lines. Make no mistake that the organizations that oversee this stuff are much more aware of the prevalence of these things than the public. That’s not to say that they’re all corrupt; they obviously aren’t and sometimes people do get caught. However, speaking from personal experience, athletes would know when to expect “random” testing. I always like to use a scene from the old SpikeTV show “Blue Mountain State” for reference to this. In the scene, the team is in the locker room when the head coach calls everyone’s attention in order to tell them, “I had a dream last night that a representative will be coming here in one week to give a random drug screening. In that dream, everyone passed that test with flying colors. wink”. You’d be surprised how accurate that scene is.