The good thing about humans is they have very well-written exception handlers built in!
Such a program is likely to be brittle and could fail unexpectedly requiring human intervention. There are also many other events that couldn't be triggered, such as the beginning of commercials for non-BBC shows, the beginning and end of popular sporting or other TV events that would trigger the same phenomenon. It's probably far simpler and cheaper to have someone sit there and press buttons, with the added bonus of high accuracy.
Such a program is likely to be brittle and could fail unexpectedly requiring human intervention. There are also many other events that couldn't be triggered, such as the beginning of commercials for non-BBC shows, the beginning and end of popular sporting or other TV events that would trigger the same phenomenon. It's probably far simpler and cheaper to have someone sit there and press buttons, with the added bonus of high accuracy.