Accuracy of death clock and coordinates

The show does a good job in the first episode of setting up the way the "death clock" works with the first death apparently being recorded on surveillance video. And many other deaths on the show happen in public places where this may be a reasonable assumption.

But other deaths don't. In quite a few cases, they happen in places out of public view (e.g., indoors, and in places that wouldn't necessarily have a camera operating continuously, with the person alone or among people who might not record a death with accuracy of seconds). In some cases it seems likely that the estimated time of death could be off by several minutes or even hours. And yet the "death clock" ticks down by seconds on the screen anyway, in some situations where the seconds are significant in preventing the death.

Even the 3rd death on the show in the 1st episode (Philip's) is pinpointed within seconds before he injects himself with a needle. How do they know that exact moment? A coroner might be able to give an estimate within an hour or maybe a bit more accuracy. But within seconds?

Initially, I excused this as some sort of comment on the Orwellian nature of our current society, i.e., that the show was assuming all of our devices around us (cell phones, webcams, etc.) are "listening" even when we don't think they are. Except that's never really addressed directly. (And if it were true, presumably many of the mishaps that happen on the show wouldn't, because we'd have much more detailed information about the past and the tech guys on the team should be making much more heavy usage of this surveillance potential through their hacking.)

One particular death that occurs later in the season really blows this up even further. Without giving too much away, a farmer dies by himself due to an accident with his farm equipment. Sure, I suppose I could make up a story about how there just happened to be a surveillance camera pointed at his farm from somewhere (or that he was carrying a cell phone in his pocket that went "offline" suddenly as it was destroyed in the accident or something, despite the fact the farmer otherwise appears to be a bit of a luddite) -- but this isn't addressed. And, in fact it's later noted this farm is important because of its isolation and the fact that it could sort of "disappear" off the surveillance grid without drawing attention.

But if the "death clock" in that case were off by more than a second or two, the traveler would have clearly died or at least come back within a seriously mangled body. I realize it would bog down the show to draw attention to how they knew the exact time of death in every single case, but there are too many cases where it seems unlikely they could have it within SECONDS.

Later in the season, it's noted by one character that time travel only became possible in the modern era due to knowledge of EXACT time of death, implied by the death clock that appears on screen. But is it actually feasible that all of these deaths were recorded with that level of accuracy? Or am I missing something?