Re: "US, Canada finally ground 737 Max jets..."
I wonder who is writing the software for this aircraft system.
Software people. They tend to rely on the hardware world being perfect, because the hardware people tent to spend a lot of time and effort masking the imperfections of the hardware world. See ECC and RAID for everyday examples. If they've been told that "this input is correct", they'll trust that the hardware group have dealt with inconsistencies outside their box.
Seriously, should this problem have not been found before these crashes?
Well, it's easy to rack up a hundred hours on a new model. Or two hundred. But a lot of these fringe problems occur so rarely, or after so many flight hours, that they'll only crop up in the wild after the testing is complete.
And what does that say about the testing process?
It is, by necessity, limited. What it says about the project overview, though, is that somebody slipped up with insufficient inputs to the flight computer, insufficient alerts for the pilots, or both. That or somebody was utterly negligent.
Most people can't (or won't) think in terms of "how can this fail". They don't want it to, so they don't think about it. The people who design these systems tend to be in the group who say "but what if" until everyone else gets bored and goes home. Somewhere, somebody didn't say "but what if" on this. Or (more likely in my opinion) they were overruled by somebody higher up who needed to ship and isn't of the paranoid mindset to consider just how badly things might go.
In other words:
Could it be a case of "Get it out the door, marketing is making a fuss."? - could be.