I also found at first the fees to adopt quite high. But after having raised a couple of litters of pups I can tell you the vet fees add up fast, even with "bulk" discounts.
Not to mention part of the fee is also used to pay the admin costs, food, heat, people to take care & clean, walk the animals, etc, etc, etc.
I'm not sure this is unusual though. My brother adopted two rescue dogs in the US and they were almost $400 each dog.
Some dogs also end up in the rescue because their owners go into care homes. Many of these homes don't allow dogs, which breaks my heart as the person is miserable without their dog and the dogs are often older and no one wants them.