For anyone who is old enough to remember when airbags first came onto the scene in cars, they were sold as optional packages. Most car manufacturers called the

For anyone who is old enough to remember when airbags first came onto the scene in cars, they were sold as optional packages. Most car manufacturers called these "safety packages". These optional packages were sold basically in the same way as you jokingly mentioned above. "Buy this optional package and when you hit a tree at 50mph, this will keep you from flying through the windshield and will probably save your life." I actually remember a conversation that my parents had with eachother when I was young about whether it was "worth it" to buy airbags in their new car. Yes, that was a REAL conversation that Millions of people had and a decision they had to make for nearly 25 years before airbags became standard in cars in the late 90s. Lots of people felt that the optional saftey package weren't worth the money and many people died through the '80s and '90s from car crashes that they would have survived had they splurged for the "safety package" when they purchased their car from the dealer. It turns out that when people are buying cars, they aren't planning on crashing them. So spending extra money that only helps them when they crash felt unnecessary. These packages could cost in the neighborhood of $2,500 extra. Which on a $20,000 car is over 10% extra! Would you pay 10% extra for a safety package if cars today didn't come with standard safety equipment? This is what led to the USA making airbags mandatory in 1998, forcing this safety feature on manufacturers in order to save lives. I imagine the 737 AoA sensors were sold as the same thing. Boeing sold this as a "additional redundancy package" or "safety package" and probably included many other features as part of a larger package. Just like thrifty car buyers of the 70s, 80s, and 90s who figured they didn't need airbags in their cars and opted out of the safety package. The budget airlines of Lion Air and Ethiopian Airlines had a good history with the normal 737 planes and figured this additional safety package wasn't worth the money.