I don't understand why would your think that a rescue dog should be easy for anyone to adopt? All rescues have already been dealt a not so great hand in their lives. The foster homes have given much love and attention to their fosters and want to make sure they are going to be adopted into a really good home that will be FOREVER. Many have been HW positive in the past and have gone through horrible treatments to get them well. Some have been poorly bred and needed extensive medical care for genetic reasons or even abuse. Other have been pulled from shelter after being nearly bred to death. So yes, rescues are very picky about whom their fosters are adopted to. It is your choice how you vet your dogs and your vetting is your business.
Rescues follow a standard of care according to the AVMA as to how a pups should be vaccinated and cared for. So if you chose to follow a different belief that is your choice but you cannot expect a rescue to waiver from a standard of care whether you agree with it or not. I am sure that you are a good pet owner but to put down rescues for all of the hard work they do is just not fair in my opinion. Foster homes are all volunteers, we volunteer our homes, times, lives and many times donate large amounts of money to help saves lives.
To me to have someone that is not aware of all that goes into being part of a rescue "vent" about their rules is just not justifiable. Like a good breeder who turns down buyers, rescues need to also step up to the plate as well and be a voice for their pups.
How about making a donation to the rescue of your choice to assist them in all of the unending work they do to save the pups that are so in need of help.