It’s because the defense lawyer industry has turned DUI cases into big business. The typical DUI lawyer makes 10-15 grand per case.
An officer stops someone for failing to stop completely at a stop sign. See obvious signs of intoxication. Completes the DUI processing and types his report.
The person blows a .18.
Guilty as all hell, right?
Well now is where the fun starts.
Did you forget to put on the back of you ticket that you were in full uniform and driving a marked patrol car? Did you forget to put down that the street you stopped him/her on was a”city street” and not just any old county road?
What about page 9 of the dui packet? Did you photocopy your BBAC card onto the continuation sheet? Did you watch the suspect for the full waiting period to ensure that they put nothing in their mouth, not even their fingers?
Did you actually see them driving or did you come upon the wreck and they were merely climbing out of the car from that side? Because their unnamed friend, who ran away, was really the driver.
Etc, etc, etc, rinse and regurgitate.
There are former DAs who created the tests who now work as defense attorneys fighting the results of these tests.