having a database of every dwelling which has had a TV license previously and currently doesn't also helps ensure a brown envelope drops on the right door mats, for years.
I moved house, let the old BBC licence shortly expire, and the old house was empty for nearly a year before I sold it. I'd go back to it once a week to pick up mail, and those brown envelopes soon arrived. They got increasingly hysterical about I was going to be visited and fined for having no licence. Then after about the third letter they'd stop and I'd hear nothing for a month. Then they'd start from the beginning again.
I tried phoning them to say the house was empty but I was led round an automated circle for 20 minutes until a robot told me to use their website. The website told me to use the phone. I'd have written to them but was damned if I was going to pay for a stamp.
They cannot have been using detector vans to find me as there was no TV there. I was probably the only house in a middle-class area without a licence - an easy target (they thought). I expect in an area of flats, squats and bed-sits, especially with a high immigrant population and some pit-bulll terriers around, they would not have bothered.