Reading comprehension owns you. What the man said(more than once), is that roving patrols catch MORE impaired drivers than checkpoints. MORE, as in a greater number than 19. So the checkpoint got 19. How many MORE might have been caught had the amount of time and manpower used in those checkpoints been allocated to being on the road, watching and catching the drunks?
So what if YOUR family got killed because the cops were too busy stopping 6,000 sober people? I bet that YOU would feel differently.