Neighbor turn you in? Why else would AC come along and issue a ticket unless the dogs were running loose? Maybe the neighbor called turned you in and they just wrote up the tickets and mailed em to ya.
News Flash
Cities and Counties struggle to find money due to poor economy!
That just about sums up all the extra effort on licensing of dogs. For years the statutes have been on the books and relatively unenforced. When the economy went down the "flusher", every bureaucrat started scrambling for sources of cash, probably to insure their survival in the parasitic world of government.
Dogs are an easy target. How many are left alone during the day in yards or even in houses. All an animal control officer has to do is print out a list of existing licenses and the addresses that they are issued to. They then go out and drive up and down the street looking for that dog in the yard, check the list. If no license they knock and if no answer just mail the "Civil Infraction". When the "low hanging fruit" of the dogs in the yard are "plucked" they just go door to door. Easy job finding dogs because all it usually takes is a doorbell or knock and any dog in the house "fruits out". Dead giveaway. Again a check of the list and a mailed "infraction notice" if not licensed.
This is easy money and since this revenue is often targeted to the animal control positions it can protect those jobs from layoff. Just like the Motorcycle cops that are like ATM's for Cities, Counties, and the State, these lowly "dog catchers" are just doing their part.
As for "getting off" on an unlicensed dog ticket? Good luck. Remember, it's only a Civil Infraction and your case may not even be heard in a real court.
Solution: Cats don't bark and give themselves away. You could also train your dog to use "Stealth Mode".
Another little factoid on animal licensing and fines. A neutered animal is usually real cheap to license. One with all their "goodies" can cost more than a car or truck to license.