I’m referring to massive consistent usage from the same IP. Most residential IP addresses are dynamic but remain fixed for weeks or months at a time. It’d be easy to see that the same IP not associated with the actual customer account has streamed every day for the past month.
Hell I bet they could go a step further and identify the exact person as well! There’s so little competition that it’s likely the account holder and sharer are on the same ISP (ex: you both have Comcast). They would know the name and account on the sharer’s source IP and, more importantly, that it’s not the original account owner.
As long as they are careful and work their way down from the most egregious offendors, it wouldn't be such a big deal.
They could also do techniques like gentle shaming "Your account has been used from 46 locations in 7 states today. We might start charging for this level of account-sharing in the future"
Hell I bet they could go a step further and identify the exact person as well! There’s so little competition that it’s likely the account holder and sharer are on the same ISP (ex: you both have Comcast). They would know the name and account on the sharer’s source IP and, more importantly, that it’s not the original account owner.