Indeed, a Toyota with a critical fatality-inducing safety defect every 200,000 trips would be rightfully viewed as a deathtrap. Given that the average trip is probably somewhere around ~30 miles that would be a fatality per 6M miles versus the standard of ~60M miles in the US, or about 10x more dangerous. However, when comparing a car versus airplanes, given that they both fulfill the niche of transportation and are to some degree substitutable, a more reasonable analysis would be fatalities/person-hour or fatalities/person-mile. For fatalities/person-hour the average flight is something like ~2 hours. In the same amount of time 200,000 cars for 2 hours at an average of 40 mph would be ~16M miles, so the 737 MAX is ~4x more dangerous on a person-hour basis than cars. If we go by distance the average flight is ~500 miles, so the 737 MAX had a fatality per 100M person-miles or is ~1.6x
safer than driving. That is just how high our standards are with planes that a plane that is viewed as an absolute death machine that is totally unfit for use is safer than its primary alternative for an equivalent distance. A plane that is 100x worse than any other commercial plane is still better than the non-plane alternative on a per-distance basis.
Obviously, this does not excuse their actions as they still made a system at least 100x more dangerous than the standard, but it should give perspective on the difficulty of the problems actually being solved. It is not a bunch of amateurs or below-average engineers who need to adopt basic practices. It is a bunch of highly-skilled professionals developing systems with a level of reliability far beyond what most software developers even think is possible. Even the abysmal processes of the 737 MAX that are far below the standard in the airplane industry would, relative to most software, be very good. It is just that the problems they need to solve are very, very, very hard and very good does not cut it when lives, not data, are at stake.