I can not understand the people that work in those places, don't they have feelings? or a consience? don't they feel guilt?
This is a question that was asked many times following the atrocities of the mid-twentieth century. People wanted to know how ordinary people could end up doing bad things, so a series of classic experiments was carried out to try to find out. The most relevant one I can think of at the moment is the Stanford Prison Experiment:
"What happens when you put good people in an evil place? Does humanity win over evil, or does evil triumph?"
The answer is counter-intuitive and highly worrying.
Take a read, it may help you to answer your question:
The Stanford Prison Experiment: A Simulation Study of the Psychology of Imprisonment
Depressingly, and rather worryingly, evil seems to triumph in these conditions. People can do dreadful things when placed into a position where they are expected to do so. The notion of free will seems to disappear quickly. This is the concensus of dozens of psychologists who have sought to try to answer this issue. And yes, people who do cruel things do feel guilt to the point that it can torture them to insanity. Following some of these experiments, at least one person committed suicide and another letter bombed one of the researchers. And I work with war veterans, a small number of whom carried out terrible acts, and even though they did it "under orders", what they did haunts them until they day they die. The nonchalance and humour are defence mechanisms, which is one of the reasons butchers and fishmongers always have a strong sense of humour.
So the question we need to ask involves those who put people into the evil place in the first place. I try to put aside my instinctive anger towards these desensitised and cruel employees (but it's hard, believe me); instead, I blame the corporations that set up this inhuman system rather than people who ended up working for them, many of whom would have no idea what the job really involved before they got hired. You can say that these employees have the freedom of choice to leave the job once they see it for themselves, but all the research (and there are many, many other examples) suggests the opposite.
Likewise, most who buy that cute little cavy from the pet store have no idea at all about the horrors of breeding mills. This is why I'm glad people are working hard to get the information out there so that one day, maybe, just maybe, this horrific cycle of abuse may come to an end.
The one positive that keeps me going is the reaction in my own country to
the chicken out campaign, and others like it, that encourage people to buy free range eggs, for example. Free range eggs are now taking a much larger slice of the market. The example is not a perfect one, I give you that; even some free range hens suffer cruelty (especially the males who are disgracefully gassed to death because they are believed to be of no use). But it shows an admittedly flawed example of how purchasing power can cause even the big corporations to change their ways. Like I said, not a pefect example, but it shows how the average man and woman in the street can change the world through our decisions.