or just damned lazy, the ones responsible should be fired.
Few years back a bedroom community called Forest Park on the east edge of Okla. City got in trouble over something similar: they were hell on '2mph over the limit'-type speeding tickets, and a guy not only fought the ticket, his attorney demanded the records on the maintenance and calibration of the speedgun.
Turned out they hadn't bothered to check it for more than two years, and when it was checked for the court it was off by 5-7mph(as I recall; it was a significant amount). They wound up refunding the fines from hundreds of tickets, notifying the state so points could be taken off peoples' driving records, and other such fun activities. I can't remember if anyone was held personally responsible for not taking care of the maintenance on the thing.