Meat from free-range chickens has an ecological footprint about 4 times higher (they grow slower, live longer, so need more water and feed, while excreting more methane, and use up more land).
It would indeed be interesting if packaging from supermarkets put some estimate of environmental footprint on the packaging. I doubt it will happen: It would thoroughly confuse many consumers that the product with the highest price has the worst environmental impact, and could reduce sales of their highest margin products.
That's considering that you only use the land for chickens, and that you get your feed from elsewhere. Multi-use land solves that problem, and can also reduce the need for feed (e.g. chickens in an orchard). Those systems can work really well when implemented & maintained by someone with the necessary knowledge and experience, and drastically reduce resource usage. However, most of those systems are not easily automatable, and thus require more human labour, which makes them more expensive overall (this might be solvable with todays AI & robots, but the resources needed to buid, use & maintain the robots would probably wipe out any resources gains).
But they'd win the packaging war you mention hands down ;)
A chicken needs 4 m2 per bird to be called free range (in the EU), a battery chicken needs less space than a sheet of paper, and they can be stacked. Then you need twice as much land to grow their feed, or more if you don't want to use intensive agriculture. This is not something you can realistically offset with multi-use land usage.
I don't particularly care whether people choose to let the environment or animal welfare prevail, but the choice should be well-informed.
Yes, basically those are cheaper because they use less ressource and thus have necessarily less environmental impact. It doesn't make sense any other way.
Capitalism has plenty of bad outcomes, but inefficient use of ressources not generally one of them.
All of this makes it very hard for people who are posturing trying to appear virtuous/moral in their choices (food, clothing, whatever). At the end of the day if you think you are a problem the best solution is to get rid of it...
All the studies about plant-based vs animal food are deeply flawed because they don't compare properly the nutritional profile and ressource intensity.
Most of what we feed to animals is waste/byproducts or just not fit for human consumption, but conveniently can be grown in less arable land.
It would indeed be interesting if packaging from supermarkets put some estimate of environmental footprint on the packaging. I doubt it will happen: It would thoroughly confuse many consumers that the product with the highest price has the worst environmental impact, and could reduce sales of their highest margin products.