I have always found the staff there to be helpful in every way that they can.
When you go to pick a dog up you have to provide ID so that they know, and can prove, where the dog has gone.
Anyone can ring up and say that their dog has gone missing, if they then send you round to someone's house to collect it, or them to yours, what are they leaving themselves open to if it's not your dog, or something happens at the others house.
Mistakes happen, I've had my dog slip his collar (he now wears a harness), and that would have meant no visible ID (he is chipped).
The £30 covers costs and is also a good incentive to put a tag on him, especially if it happens more than once (certain dogs are at the pound almost weekly).
You can get them for a few quid at most pet shops, Pets at Home even has a machine by the door to make them for you. If the dog had a number I'm sure the kind person who found him would ring that number before the pound.
If you don't want to trouble the "kindly old gentleman", or deal with the "mean spirited staff", you need to put your details on the dogs collar