Thin grocery (and garbage) bags are sheet polyethylene, the plastic of which is just as recyclable as milk bottles. They are not accepted in many curbside recycling programs because the separation tech is not designed for them, not because the plastic itself is not recyclable. They are recyclable (and frequently recycled) via dedicated collection points. (Most of our grocery stores have them.)

Yes and no.

They are recyclable. But because of their low weight, high amounts of contamination, and constant ability to get stuck in conveyor belts... Thin plastic bags are more trouble than they are worth.

It's like Aluminum foil. Recycling plants are paid per ton of recycled material, and it takes lots and lots of aluminum foil before a ton of Aluminum is saved up.

Except plastic is way harder to recycle than Aluminum (requires higher purities).

It depends of course, on where you are and what type of recycling schemes are available. As a general rule, “don’t put plastic bags in with your regular recycling” is correct. But we have a very successful ‘soft plastic’ recycling scheme in New Zealand that results in useful products (I have 52 fence posts made with thousands of recycled milk bottles and plastic bags).

Yeah, my location also has special containers for clean plastic bags. But general recycling no longer takes them.