There is digital, digital and digital
OTA digital is ATSC and by federal law all TVs sold in the US must receive or must be clearly labeled that they do not. .and I think that last "Labeled they do not) has expired but.. not sure.
This leaves QAM digital
And ENCRYPTED QAM digital
Now many TV's (The Element brand is the only exception I know of) have done QAM for along time... NOTE: Though Element is the only brand **I** know of, well, this does not mean others can not.. Just I don't know it.
BUT: the problem with QAM digital, ATSC digital and Analog is this.. A subscriber can go to Radio Shack, Dollar General, Wal*mart, Best buy and a long list of other stores and get a SPLITTER, and some coax and run a 2nd line to a 2nd TV or a 3rd, or 4th and not pay any additional fee to the cable company.
NOTE they are already over charging you.. Delevering about 10 dollars worth of service for 100 dollars a month type over charging you, but oh, we can't have you adding TV's without our getting an additional FEE.
So some cable companies (And I won't name names because..> Well.. Liability is attached to names) have gone to ENCRYPTED digital.. that way you need a Set Top Box for every set. And they can charge you an additional fee per set top box.