Bittorrent is legally clear-cut, because the sharing part is a clear copyright infringement (you are distributing the work without authorization).

Streaming (typically) isn't that clear, because consuming the work is technically not forbidden by copyright law in most countries. It's a bit like reading a book in a bookshop without buying it.

Detection is fairly easy in both cases, they just cannot go after consumers.

For example, my IP address is paid for by me, through a run-of-the-mill ISP subscription. Does that make me legally liable for all the activity of the other person that lives with me and uses "my" network for all their private internet traffic?

I guess there are laws about facilitating piracy, and whatnot, but you can't reasonably expect me to screen all my fiance's activity on the network. Most of it is encrypted anyway. I can't be on the hook for that.

I'm privileged in that I have an ISP that feels the same way as I do about this. They've fought for the privacy of their subscribers before, and will likely keep doing so in the future, because an IP address does not identify any individual.