I agree with much of what you have said, micro chipping is a great idea, but only if you have a microchip reader. It's already a legal requirement for dogs to wear an identity tag and many dogs don't have them either, so I think chips would only go so far. Where we do get dogs with tags or chips we can reunite them, the first time without charge. If they are repeat offenders it starts to cost. In most cases they never get as far as us because the finder returns the dog.
At the risk of making work for myself it's easy to find out the costs if you need to, just put a Freedom of Information Act request in.
I can tell you that it costs me approx £1000 pcm to kennel stray dogs, if the owners are traced they can claim the dog only after they have paid all the costs of kennelling (inc collection and vets fees if necessary) and the Statutory Release fee of £25. The £1000 relates to the costs of kennel rental and those that are not claimed and have to be re-homed. This figure doesn't include the proportion of my ACO's salary costs. Add that in and you can probably add another £2-3K a month to the figure.
I can say that the people we use to re-home don't pts dogs unless there is a medical need to. It puts a massive strain on their resources but they will not do it. They also neuter all their dogs to prevent indiscriminate breeding, which is the single biggest problem we face.
Oh and by the way the Police won't deal with stray dogs anymore so there is a real problem in getting strays dealt with out of normal hours, the costs to councils of running a 24 hour reception facility would blow my annual budget in under 2 months. It's a truly grim situation and I can't see it getting any better any time soon.