If you run 60,000 chickens I think you will understand a few things. From what I know, flocks that size are medicated in bulk. Individual chickens are not diagnosed seperately, or treated seperately.
Health and hygeine involves walking around picking up and throwing away anything too sick / dead, to run away. Other chickens still capable of running away may be suffering horribly.
Mass chicken farming makes beekeeping practises pale by comparison. However that does not mean the owner is not interested in his birds, it means there is an economic threshold he cannot go past and survive financially.
Just for the record, there is quite a move in my country to improve the lot of farmed chickens, and I'm in fiull support of it. I buy organic free range eggs that cost several multiples more, but I know that chickens were not brutalised to cut a tiny amount of money from my budget.