Re: "US, Canada finally ground 737 Max jets..."
I think they were waiting for some hard evidence. Once it arrived, *grounded*. No crashes occurred in the USA, and so the decision was "not wrong".
A grounding of all planes of that model would disrupt airline schedules, and so I think they wanted to avoid that happening. Now that there's evidence to ground them, safety first.
I read the linked article about what the system does, and there seems to be too many "it takes over" scenarios associated with it, almost like brakes in your car that apply themselves in situations where it would be smarter to accelerate or steer around something.
In the case of a stall detect in which the instrumentation had iced up (let's say), it could drive a plane into the ground, if I interpret things correctly.
Pilots are probably used to using the 'on the yoke' trim adjustment, but apparently if you flip to 'manual trim control', you have to spin a handwheel instead, NOT something a pilot would normally want to do. And going to 'manual trim' apparently disables the system, but it seems kind of *obscure* to me that THIS is the only way to shut it off.
I think an alarm should sound, warning the pilot, before this automated system kicks in. Something like "stall alert" followed by a well documented 'correction' operation that's also announced, and a BIG FAT KILL SWITCH to take it off line in case it was caused by instrument error.
Anyway, FAA will now investigate no doubt and come up with something. Boeing will have to re-certify, I bet.
Biting the hand that feeds IT
