Almost all digital-cable TVs can receive and decode both ATSC
(digital) and NTSC (analog broadcast/cable) signals. *They can look at
any proper 6 MHz slice of the broadcast spectrum, look at the signal
in that range, determine whether it's NTSC or ATSC, and display it
properly.

Not around here. Digital only TVs are starting to proliferate since
analog TV is no longer broadcast, it makes little sense to pay for
obsolete technology any more. They only have Scart inputs, so if you
want to tune to VHF/UHF you will need an external analog tuner.