My mother breeds quail for meat/eggs.
Even with a decent amount of space some females will attack and gravely injure their flock mates (when they reach a certain age/size). More than one male in a cage and you can almost guarantee a bloodbath.
I doubt any place that is breeding quail as 'feeders' will be single housing every individual of their flock. Look at enough quail feeders and you can be certain there will be injuries (some of them probably fatal).
Of course with the nature of forums I'm sure someone will jump in and say that they keep quail as pets and every one of them is a well-tempered angel-if you do 'xyz'. Yeah right...![]()