This is standard for how they do technical inspections. They can’t check every rule on every car, so they check just a few important ones for every car (fuel, weight, etc) and then do random checks on a handful of cars each for others. The idea is to prevent it from being worthwhile to break the rule, while also requiring substantially fewer resources. That’s probably also why the penalty is so steep: if it was a slap on the wrist that you had a small chance of being caught for, you might as well just always run out-of-spec.