The simplest methods block known datacenter IP ranges like you thought. More will score it based on several heuristics and a reputation over time. If you get 100 different users connecting from a single IP, it's probably not someone's home internet connection.
Or, their so-called "smart" TV is acting as a proxy without their informed consent.
There are also third party providers of IP annotations to classify known VPN address ranges that content providers typically subscribe to blanket block providers.
The reason for this aggressive approach is streaming apps all need your IP as core signal for tagging your region and all content licensing is region locked (even on YT).
Netflix are/were the most relaxed about it , and for long time would only buy content if they got global distribution rights, but not anymore. Many VPN ads specifically used to market that you can watch Netflix geolocked content.
[1] IME they block DC IPs too although not needed for blocking professional VPN, even self hosted OpenVPN on cloud box usually gets flagged.