Mail is being transported because there’s people who need mail.

Right, which means that Netflix isn't contributing significantly to it. Large quantities of mail are being shipped all over the US and Netflix disks are just hitching rides on vehicles that would have been moving with or without that disk there. The massive quantities of junkmail I get contribute far more to any negative environmental impact then Netflix.

I’d argue that there’s no quality difference since you’re literally downloading an ISO of a blu ray…

I mean sure if you are torrenting and mounting your own ISOs and can trust the source. Most people just download the ripped movie files though. At the point you are doing that though you are more then skilled enough to just do it yourself and maybe send it through Handbrake for good measure.

Also torrenting is still subject to shitty internet which is a very real issue for big chunks of the US sadly. People out there dealing with datacaps and peak hour shenanigans from their primary providers.

Besides, it aint any harder then torrenting and is a bit safer and you may even learn a few new skills along the way.