Same reason normal, middle class people in decent vehicles get pulled over for expired tags or burnt out brake lights, yet the shit boxes with 3 tires and a plastic bag for a windshield keep on rolling.
LOL. We actually have strong evidence that vehicle safety inspections do absolutely nothing to reduce accident rates and that's why 13 US states don't do them.
And yet, my level of danger to society is also close to zero.
This happened with me right after they reverted the pandemic decision to allow alcohol there and I didn't know. I was drinking in good faith like I did for several months when they allowed it during lockdown.
Still, it is very frustrating that the beer would warrant a couple of park rangers to approach and enforce, while just a few meters away someone was doing hard drugs visibly completely out of their minds and screaming at passer byes.