I agree that we do ourselves a massive disservice by describing these thieves as CFs.
Why do the police and security guards ignore older people who steal, even when they have them on CCTV? It's kind of pointless them being there at all, really, as in that case, any thief can just send their gran or grandad out to steal on their behalf - a reversal of the way that criminal families train up their kids in crime and then keep moving on to the younger ones once the older ones reach the age of criminal responsibility.
PP is right that many of them are younger thieves who just got old; similar in principle to when we meet deeply unpleasant middle-aged people who will answer the question 'what eventually happens to school bullies?'.
I agree that, the more they can get away with, the more they will try; so by stopping and frightening them early on in their criminal career, who knows how much worse crime could be prevented?
I definitely don't see why we should show any clemency to old thieves when they are quite clearly happy to steal from children. "I thought it was there to take" is just caught-red-handed-thief-speak for "I thought I could get away with taking it". As a general rule, people will usually put out a sign inviting you to take things, if that's the intention; if there is no sign, they probably don't want people to steal their own garden property.
We have several scrap men who go door to door. They can be very handy if you have an old washing machine, whatever, actual scrap to get rid of, but some of them are quite brazen in what they will take - hoping you won't notice, but coming out with the rubbish "But we thought it was put out for us to take" excuse. Supermarkets lose a good number of trolleys to them, too, when customers take them home with them and abandon them outside their houses - those go straight up into their truck too.