Depending on the country, it’s pretty common for most milk production to be cows kept in extremely cramped conditions indoors with little to no space to move and fed processed grain instead of grass. It does make the milk taste worse, but it can be so much cheaper that customers don’t splurge on the more expensive milk, so don’t know what they’re missing. Even if you only ever see cows outdoors, you might also see low-welfare dairies and just assume they’re warehouses or factories and aren’t full of livestock, as a factory farm can look just like any other large industrial building.