Social norms are what instituted and what ended slavery. They don't come from social norms but rather exist as long as social norms tolerates them.
Lack of understanding, lack of wealth, lack of discourse and so many other factors are what play into many things being tolerated or not tolerated.
It's rather hard to get a man who can read to sign a bad contract compared to one that can't read.
Thus things naturally improve when most men can easily afford books and things.
There's a million things that impact almost everything everyone does just by their existence or non-existence.
you get far more plaster screwed and for far cheaper with the commercialisation of screwguns and things.
that's an obvious truth
same with building
and it becomes safer
thus why we have less deaths and things
small transport of goods and more advanced lifting systems that are much stronger means less accidental loads due to dropped materials.
All these things also affect social norms in their ways, like how much are willing to pay for x, how fast they expect it to be done, and so on.
they also affect moral standards however how could you leave a floor rotten and have people work on it, knowingly? It is exceedingly easy to know better now, and it is hard to ignore, and it's quite easy to deal with, but one chose not to.
Same with mining and silica production and so on, it's easy to protect workers from respiratory damage because protection has been commercialized.
thus it becomes no longer socially acceptable to expose your workers to that unless you go to somewhere like Africa and do it there instead. But even that is changed / changing.
