And training. Training is massively expensive. You gotta train pilots, crew, mechanics, baggage handlers, etc, etc. The more situations in which you can say

And training. Training is massively expensive. You gotta train pilots, crew, mechanics, baggage handlers, etc, etc. The more situations in which you can say "the new one is just like the old one you know" the better. Part of the reason pilots weren't initially properly trained on the MAX8 was because Boeing and the customers were winking and nodding at each other and trying to perpetuate the farce that the new plane was the same as the old plane and giving the pilots minimal training was part of that. If everybody knew how the new MCAS system worked there would likely have not been any crashes but that couldn't happen because it would have created a paper trail that indicated the MAX8 was pushing the limit of what was allowed under the old FAA cert.