The current FCC regulation says that for as long as a cable system continues to offer analog service to any of its customers, it cannot encrypt the digital signals that
it carries for the local stations. Only when the system goes completely digital is it allowed to encrypt the locals.
An important thing to remember is that the only reason that the cable systems even deign to offer the cheap ($20 per month) package that contains the local stations
and a few public service stations is that federal law commands it. If that law were not in place, the cable companies would not bother to offer an inexpensive package.
The cable companies regard those low paying customers as something of a nuisance. They want everybody to sign up for a high priced digital package, even if there is not enough good quality programming to warrant having so many channels.