AAS has been exposing how the business of pet disposal works for years - how it promotes a lucrative culture of pet owning and abandonment. It is all based on market forces. There is money to be made in all three parts of the pet business. The manufacture, sales, and disposal. All make money.
Disposal is necessary to deal with unsellable product. The first two parts could not operate if there was nowhere to get rid of unsellable product. The disposers are the pounds and SPCAs that get unlimited free product by having unlimited surrender policies. The free product can be sold, if sellable, and what doesn't sell is cheaply disposed of by killing. As long as there is a readily available disposal system to support the manufacturing and selling parts, manufacturing and selling will thrive. Without a place to dispose of unmarketable product, the system would clog up and founder.
In the pet industry, product is unsellable for many reasons: too many of one breed is produced, the product is old, or sick, or inconvenient, or too much work, or in the case of dogs, ruined and dangerous by being mistreated. In the pet industry there is a lot of free product for the disposal part of the industry. But all that free product necessitates a lot of killing of unsellable product. If you accept all free product, a lot is going to be unsellable and will have to be killed. Product that is unsellable because it is sick will be sold "as is" or killed.
Wherever there is a vacuum, the market fills it. If there is a way to make money it will be made. And of course, there is a way to make money being the disposer of second hand pet product. If reselling or killing pet product is marketed as humane animal welfare then the business actually attracts donations from animal-lovers.
The business requires a lot of killing of unsellable animals but the SPCA can no longer kill with impunity - the internet is united and watching. But what to do? The dilemma is that the BC SPCA still has an official policy of unlimited surrender but it can no longer kill as many animals as is necessary when surrender is unlimited. If it changes its unlimited surrender policy, good-hearted but uncomprehending animal lovers will get mad and stop donating (not realizing that their donations all these years have gone in part to clearing out SPCA facilities to make room for the next load of free product).
The crunch is coming though, because the market is flooded with unsellable product that no one can get away with secretly killing anymore and all the disposal centres are full and there isn't enough money to keep all the unsellable alive. Clearly a market correction is needed. If the places where owners can freely dispose of their unwanted pet is limited, pet sales will fall off and so will production - the breeders and puppymills.
(Read many more posts on the subject of the pet disposal business on this board by putting "surrender" in Find. One is here: http://www.animaladvocates.com/cgi-bin/newsroom.pl/read/2700 Unlimited Surrender Policy: The SPCA's Moral Psychosis