Preventing lamps being stolen / thieves' motivations
I've never had a problem like this with dynamo powered lights. While thieves seem to be interested in clip-on lights, they don't seem interested in lights that need a wrench to remove.

Of course, adding dynamo powered lights means adding a dynamo first, and it's important to take either a hub dynamo or a good bottle dynamo. The vast majority of bottle dynamo models is utter crap! The added advantage of dynamo powered lights is that you cannot forget to charge them, and they'll serve you well should you decide to ride through an entire night...