I want to start of by telling you that I have a solution to the problem and if you continue reading you can share this solution with others and hopefully one day the canine world will be better off, but I will keep this short and simple because there is no point in dragging this post out and over complicating to the point no one wants to read it. Here we go.

First let us address the problem. Back yard breeding, puppy mills, irresponsible owners, unethical breeders and spontaneous adoptions. Why are there so many dogs living in shelters that need homes? 

Reason #1
Back yard breeders and puppy mills that breed with no purpose other than puppies are cute, they want to make a bit of cash or in the case of puppy mills they want to industrialize and make profit on selling large quantities of puppies. No health testing is done, sometimes the parent dogs are closely related, temperaments may not be considered, there is no pedigree etc. The reason Back yard breeding and puppy mills can lead to more dogs in shelter is simple. 
-The Dogs are more likely to have health issue or temperament issue because less care has gone into genetics and whelping of puppies.
-The price of these puppies usually reflet the amount of time and care that have gone into breeding them and the low price point opens the door for spontaneous adoptions from people that aren't thinking through the decision to bring a new family member into their home.
-Another important factor here is that there is no puppy contract and no backing of their puppies that says they will take back a puppy that can no longer be kept by the adopting party.
-For puppy mills specifically, the large quantity of puppies alone is a red flag that this is not ethical or sustainable. If it feels wrong don't do it people! 

Reason #2
Irresponsible Owners and Spontaneous adoptions.
If someone adopts a dog and they are not thinking this decision through or are not committed to the responsibility of caring for another being, it puts stress on the dog when they need to be rehomed again and again. 

Reason #3
Unethical breeders, it is easy to call yourself whatever you like but in my opinion it is not ethical to rehome retired dogs from a breeding program and ethical breeders should always state in their contracts that if a person adopting from their program can no longer care for a puppy that the puppy is to return to the breeder. Ethical breeders need to  not over breed their dogs, their dogs need to be their family first, carful consideration of health pedigree and temperament should be priority, a pet only(Spay/neuter) clause needs to be in place unless otherwise discussed and they need to back their dogs and be responsible for/take back the puppies they produce if the home they have placed them in can no longer care for them.

The solution?
-Adopting from a Ethical/responsible shelter and from an ethical/responsible breeder are equally good options and are the ONLY way anyone should be adopting their furry(or not furry) friends. We need to stop arguing about it because we need shelters in place for all the dogs that have wound up in bad circumstances and we need ethical breeders to continue the beautiful breeds that grace our earth.
-We need more funding or affordable options for the the spay and neuter of strays and pet only dogs.