As an example, if a producer declares they meet a specific standard this could mean they voluntarily undergo regular audit of their entire process including how the cows are treated.
We do this for many products and services. Here in Poland, eggs are regulated in many categories from hens kept in cages to free-range. When you buy eggs they are all individually stamped with a mark that clearly indicates how hens are kept and fed and you, as a customer, can choose the more expensive product but with a knowledge that you get what you pay for.
It seems like it's just not very effective, most people are looking for the cheapest alternatives as one would expect - https://polandin.com/36653246/consumption-of-ethical-eggs-st...
But I agree that packaging for products contains multitude of markings and without extensive research it is difficult to recognize which markings are regulated and which are not and what they mean exactly.
The reason why factory farms exist is to meet the increasing demand. Farmers have every economic incentive to try to raise the animals in the cheapest way possible.
Still the cow is a prisioner, it has its childs taken away at birth and shot and gets impregnated immediately after, to keep producing more milk.
If the cow stops producing as much milk, it gets shot as well. Even if the cows lived a live chilling in the fields, all of this would still happen.
This is the "market for lemons" problem: Consumers can't tell actually humane treatment from fake, which ends up economically pressuring farms to cut corners and go towards the fake.
You could register a trademark and have a certification program for "humane" milk / meat producers to use. Then go around raising awareness of what "pasture-raised" and "grass-fed" really means. If you do a good job of communicating, people will be happy to pay the extra $0.50 (or $1) to know the cows are actually chilling in the fields and not cooped up in a pen.