They're not "ok" with the level of cruelty but in a pervasive environment of limited culinary and social choices, they're okay with living with that knowledge.
Personally, I think you get further raising better people than trying to impose a moral standard in a population that (for the most part) eats diets that hamper cognition and volition ala high sugar and ultra processed crap. Intermittent fasting and a decent diet would do much more for the quality of moral calculation of people than telling them that their entire culture is morally bad. Because we're humans who utilize different strata of values, not mere moral robots.
To paraphrase Nietzsche, the moralists and priesthoods of the world devalue the very small things which give arise to moral judgment: Diet, climate, and habit.
> Definition of proponent: one who argues in favor of something
Even if people are enabling something doesn't mean that they are proponents. Let's stop with the newspeak and use the correct words for things please.
Not everyone has the money to choose differently.
At times there is no choice. This is especially true if you are a 15 year old. At 15, you basically eat what your parents eat. You can't generally afford food. You can't always just get a job if your parents won't provide education and/or if your school decides your grades aren't up to working. Oh, and you can't work all that often due to child labor laws.
At times, the actual choice is a bad one. Take eggs, for example. When I have the choice, I choose eggs from hens with larger cages. I realize these are hardly large, but they are better than the alternative. I've only lived one place that I could buy eggs directly from the source (during summer time) - but I'm literally an ocean plus some away from that now.
People honestly need a little bit of animal proteins lest they must take supplements. (Truth: I take vitamin D, as I can't make enough at my northerly location). I'm also mostly vegetarian. I eat fish once a week and I eat eggs and cheese.