Tribune provides what they are provided, nothing more, nothing less. It's the Networks who provide the data to Tribune that need to provide accurate data. Tribune simply gets the data from all providers and puts the data into one database. They don't modify it in any way.
Runner is correct; the data flow is from the station or network to Tribune, then from them to DTV, and certainly not the other direction. And the networks and stations don't really provide the information, because they outsource that to 3rd-party companies that aggregate that info themselves. Those sort of services have proliferated since PSIP because stations don't want to hire somebody to do all that data input and management, something not required in analog days.
And as I said earlier, the start times can be any time now, while they were customarily always "straight up". The reason is automation; if you have a bank of computers handling your P2Air, you no longer need the Master Control Op to handle the math, which was always much easier for the Op to do when they started from "straight up"; if a MCO got a show started earlier or later than that by mistake, they paid for that by having much more complicated math necessary to roll commercials when they needed to be; it added yet another conversion factor using "clock" math rather than decimal math.
Of course, it's getting to where we don't need the MCO at all; all we need is power, a bank of computers, and air conditioning. You don't even need lights, monitors, switchers, or even office chairs, because there is no longer anyone to sit in them and watch the monitors while pushing the buttons.
While as a Broadcast Engineer I am an automation system specialist now, I come from the days when there was no automation and the MCO had to fly by the seat of their pants, rolling each event manually 5-7 seconds ahead of when it was supposed to air. That is not as simple as it sounds when you are rolling 6 commercials back to back and each has a different length and some may have different pre-roll times. Instead of roll-take, roll-take, you could find yourself rolling event A, then rolling event B, then taking event A, then taking event B; not exactly intuitive, and a tricky skill to master.
And in the days of videotape, the show would have a pre-made 2:02 black hole built in, so that the show could continue playing back (in black) in the background while you inserted 2 minutes of commercials to the air.
The reason for that walk down memory lane was not to reminisce, it was to point out the difference. Now everything is file-based and controlled by computers. That means it is non-linear in the way a DVD is non-linear, and that you can program a spreadsheet list to run a playlist where any event can air at any time with nothing restricting it.
The end result is that programs can start any time they want, and can be stretched to include or compressed to exclude as many commercials as they want, and the commercial breaks become elastic; adding a commercial at the last minute anywhere in any commercial break used to be prohibitive, but now all it takes is a couple of keystrokes.
And that is what is at the root of the near chaos we are dealing with. FOX can (and will) start a program at 8:33:18 if it serves their purposes, but what does that mean for recording it? While they do customarily provide an offset (start time scheduled for 8:33, for instance) the granularity is only to the minute on most if not all DVRs.
Thankfully, the smarter minds at DTV created smart padding, which mostly makes this not a problem. But it also depends on the info being close to being right in the first place; If NBC wants to start Deception
at 8:59 but does not include that in the metadata, it defaults to 9:00, and you've missed the wrap-up that updates you on last week's show.
So we have ways to deal with the chaos, but it all boils down to correct info and passing that info along all the way to the DVR. If the data is correct, no worries. But since there is a human factor in there, the data isn't always correct, or doesn't reach all the way to Tribune and to the DVR.