There has been zero reason to physically disconnect the hookup since analog cable was phased out 15 years ago.
It can still be cheaper to send a guy out on service start to ensure the existing hookup is of sufficient quality (hasn’t degraded or been chewed or cut by the last owner) and the new customer isn’t trying to hook it into their aerial or old satellite dish or something. Or if your records are spotty and aren’t certain there’s an existing hookup.
You're right that they probably don't disconnect it. Honestly, I've never considered what happens when it's disconnected, as it's always been when I move out of a place.
Needing somebody to show up to connect it made me assume someone disconnected it, but a status check makes more sense.
It can still be cheaper to send a guy out on service start to ensure the existing hookup is of sufficient quality (hasn’t degraded or been chewed or cut by the last owner) and the new customer isn’t trying to hook it into their aerial or old satellite dish or something. Or if your records are spotty and aren’t certain there’s an existing hookup.