Another reason for simultaneous power-and-cable TV outages is plant damage. If a poleline is damaged (ice, wind, drunk driver, house fire) it's likely to affect everything on the on the line: power, cable TV, and landline telephone. In such situations, the power company always gets its repair work done first; cable and telco crews can't get near the line until the power crew has finished its work and declares the area safe.
All of which means that cable TV indeed stays out until after power is restored. But it doesn't mean that the same customers are affected. Depending on the topology of the cable network vis- a-vis the power network, it's possible for the cable signal and electric power to be running in opposite directions along the same poleline. In such situations, a damaged poleline would affect different sets of customers. A severely damaged pole at a critical intersection could knock out power in one direction, cable TV service in a different direction, and telco service in yet another direction.