One explanation might be autopilot engagement. In my 20 years on the plane I can count maybe 5 times when the Pilot Flying engaged the autopilot below 3000 feet. I usually wait until FL200 or therebouts. My other western counterparts probably behave similarly. Maybe that masked or prevented the circumstances that caused the LionAir crash. (I am not ready to lump Ethiopian yet.) As news outlets have correctly noted, many countries compensate for low flight deck experience by enforcing strict use of automation. That trend was supposed to reverse worldwide after Air France and Asiana. But the wheels of habit turn slowly.
I cannot claim the slightest understanding of MCAS other than the conflicting descriptions I have read in news feeds. Airlines and Boeing have been mum. But I do understand the trim system (the sole control used by MCAS to provide the nose down moment). It could not be more simple. Its two big wheels on either side of the throttles that turn old fashioned cables connected directly to the stabilizer. Two electric motors are bused through the same cables. Those motors allow for pilot electric actuation—moving the wheels feels a little silly in a big plane—or autopilot. There are also different trimming speeds but that is getting unnecessarily deep. The important thing is that electric trim can ALWAYS be easily cancelled by flipping the two disconnect switched next to the throttles*. So there will never be a need or an impetus for future pilots to try to “trick-fornicate” the system. A safe override already exists. The issue with MCAS has always been one of training and full honesty with the pilots flying the plane. If they had done that, then there likely would not have been a problem. And because of that, the future looks promising.
Now @BeachAV8R touched on the other problem which is a total mystery to me—the AOA input to the system. Why is it, or is…err…is it sensing a stall? Obviously in neither crash was a stall anywhere near imminent. So that’s a million dollar question.
*news outlets also claim that clicking electric trim will also stop autopilot trim. While that may be true, seconds after you let go AP trim resumes and the effects are cumulative. After a few cycles of this you will find yourself with full aft yoke and still headed for the dirt. The only effective solution is 1) AP off, 2) Stab Disconnect Engage, 3) recover with elevator and manual trim (the wheel)