It's pretty obvious that there's a stark contrast between Fred and Jeff going halfies on a service they wouldn't otherwise have bothered with, and an IPTV service that splits that service down to tiny, minute fractions, far outside of the fair use on the account (ie 2 separate IPs at one time).
Almost all streaming services limit by simultaneous IPs, since it's almost impossible to prove that Fred wasn't watching on one device while Fred's brother who lives in the same paying household was over at Jeff's watching on his own device. The fair use policies are set up like this deliberately, because sharing between two people is usually considered likely to incur a profit that wouldn't have otherwise existed, rather than a loss. The more fractionalised the one legitimate stream becomes, obviously the more severe the loss becomes. It's a conscious concession, and therefore treated differently by providers to large scale organised piracy.
Of course it's a stark contrast between IPTV and account sharing, but Jeff paying Fred for usage of his account or 10, 100 people paying Fred, it's still basically the same thing. Penalty for Fred is obviously more severe with 100 users, and IP owners are more intrested in stopping Fred than Jeff. But if Jeff want to watch legally he should pay IP owner not Fred.
Usually when you pay for the right to use a media, you pay for the rights for your household. So, sharing within household is ok and as you say, it's virtually impossible to prove that this IP wasn't in use by someone belonging to your household but using another IP address. But when the technology arrives and is accepted to use, like a universial online ID, then I'm sure you won't be able to share accounts outside of family anymore.
A few years ago, before IPTV/online streaming, people used to do card sharing for satellite service. Both on larger scale with dreamboxes, but also on a smaller scale like buying a legal twin card which your friend pays for and uses. Small scale, still piracy. Which is why they started locking cards to some hidden ID in your box's CPU when the technology allowed for it.
