It's not a chengyu. More like a local slang. And based on my findings so far, it could either mean... #1. The police are checking every single vehicle, not sparing even a single one. OR... #2. Every vehicle the police checked turns out to be guilty of some infraction. But I am not sure. Maybe both my guesses are wrong. If you know what that phrase means, let me know. Thanks!
一猹一个准, just want to type this out....... haha Edit: sorry for necroposting sorry for following the day 1 members examples.