I guess the question is what the OP considers the cost of a false alarm to be.
Because you're right of course. Lots of things can happen that put you out of communication for an extended period. Communications is more and more ubiquitous but phones and laptops break. The US still has rather large areas with no cell phone coverage. And so forth. In the past 10 years, I'm sure there have been multiple times when I've gone more than 30 hours with cellular service or WiFi.
I think it's mostly an age-related thing but a lot of people just can't imagine not being in touch almost constantly. There was a discussion just the other day where someone was worried about being tracked at protests. But "Just leave your phone at home?" basically did not compute.
In general, for a rare event, it can be a difficult problem to activate on the absence of a signal fast enough and reliably enough to be useful, without having false positives.