Changing your computer’s time to the past used to be a great way to prolong 30 day trials or pay-by-the-year software in the 386 and 486 days.
Why would you need a GPS for that?
GPS provides high quality RTC signals. So the TV could update its time with high accuracy via GPS and countdown a timer.
Thankfully the majority of people use their TV indoors.
All you need is to glimpse 1 satellite for a short while if you're looking for a roughly accurate time.
You need 3 to get a position fix, but fewer will still give you the time.