Netflix has no association with this ISP, you do. It's your choice to request Netflix streams for delivery through the ISP. Blaming Netflix for this would be like an apartment building blaming Amazon for delivering too many boxes to the mail room.

The users are paying the ISP to have that content served to them through their connection.

Is the ISP mad that more users are using more of their promised service allowance? Too bad, maybe they shouldn't oversell their networks.

The traffic is generated by a user making a request for the movie. It isn’t like Netflix is just sending movies to users at random.