The Fredericksburg Police are conducting illegal searches under the auspices of handing out gift cards for good driving behavior. But you will notice that the officer damn near sticks his head into the vehicle, which would allow him to smell alcohol or marijuana. Cops cannot just stop your car and stick their head in for a sniff, that is illegal. But if you stop for them, and are stupid enough to roll your window all the way down, you are basically giving them consent. Another jurisdiction tried this "technique" several years ago and stopped after being threatened with lawsuits. They are playing on your ignorance of the law.
https://www.nbcwashington.com/on-air/as-seen-on/Fredericksburg-Police-Reward-Good-Drivers_-Pedestrians-With-Gift-Cards_Washington-DC-565555832.html