I have my car filled with regular cheap green and never had a problem with the cooling system besides a cracked radiator at 130k miles. Original equipment was Toyota red coolant.
Yep, used cars - was the coolant ever changed and if so to what and if there is a bleed valve was the system burped? The average driver seems to not realize there is a need for cooling system maintenance.
Pep boys Proline, Chevron and Trinity that I know of. We used to use Trinity at our shop. It's recycled and has the SCA addatives for HD diesels. The supplier gave us a better price on the Chevron so we went to that.
I think most still make it just that the stores don't stock it.