We all have to work with what's available. I do my best to choose healthy chickens from good stock & provide a good environment but the sad truth is I'm lucky my death count isn't a lot higher due to environmental factors.
If I had the space I would run a free range closed flock & breed for hardiness & longevity, not egg laying or meat. I don't have that luxury. Given the nature of the chicken outlets around here my choices are:
1.buy dubious quality unvaccinated birds from backyard breeders
2.Buy a hodgepodge of vaccinated heritage birds because none of them are available in large numbers
3. Buy hybrids in large quantities to have a single breed flock knowing they will have short lives & possibly very nasty ends.
I've gone with number 2.
We then run the gamut of council regulations which tell me how many birds I may keep, & under what conditions. [ Here that means they must have access to a coop & be contained in a run]
Trying to change any of this is a head banging exercise because chickens are seen as livestock with no inherent worth of their own.
In this country @ least, I think backyard practises are improving. As chickens are seen as both pets & egg producers owners are attempting to give them a higher quality of life, unlike when I was a kid & most families on a 1/4 acre block kept chickens in a run down the back in pretty awful circumstances.
Improving the breed quality is out of my hands.