RE: Is the "system" taking advantage of Pet-lovers?
I believe there is a certain level of responsibility that you take on when you get a dog. I don't really believe the system is taking advantage of us, though I think some people have difficulty separating what is necessary for the dog's emotional and physical health and stuff that we buy or do that are really for our enjoyment not the dog's.
For instance, one of things you mentioned, shots, I feel are a necessity. They are for the protection of your dog and the protection of the people and other dogs around you. The rabies shot is required by law for good reason. Where I live there are low cost vaccination clinics at local shelters and veterinarians often have one day a week with reduced prices. Seniors usually can discounts as well. So, there are ways to save on these necessary things.
You should also get your dog veterinary exams routinely. Is it necessary every year? Probably not. But, if you note problems, it's your responsibility to take your dog to the veterinarian. After all, the dog could be in pain or suffering.
When it comes to food, I think you should attempt to buy the best quality food within your means. Do I think every dog needs to be on a wheat free diet? No, I don't. Do I think every dog needs food with all these supplements added? No, I don't think that is required. But, if your dog has an issue, then a special food might be the best thing for him/her.
I do think that veterinarians sometimes push things that your dog doesn't necessarily need. However, if you have a good relationship with your veterinarian they will know your economic means and they will also allow you to make decisions rather than pushing tests or medications on you. They will, also, try to work things out, to find more affordable options when available. I think if that once you feel your veterinarian is pushing services on you because they can, then it is time to find a new one.
There are things that are necessary to the quality of life of my dog--and some things she doesn't need at all. She does not need a new toy every week and she doesn't really need clothing given the climate that we live in. I buy her two types of dog treats, but she doesn't need 20 different treats to choose from. She doesn't need a $100 dog bed but has a comfortable, cheap bed to sleep in.
So, I would say if you take on the responsibility of a dog, then you must be ready for certain costs that are inevitable. If you cannot afford to feed your dog or provide basic medical care like shots, then it probably isn't something you should do (I mean you in general).