We literally had planes crash because Boeing was refusing to put the money down to do a proper development.

Yes, and look at their shares price.

A falling share price doesn't un-crash the planes.

No but it gives a strong incentive to behave differently. If it doesn’t, an other player take it’s place.

The stock did not move as much during the time of the Max news as it did recently due to the Coronavirus situation.

That doesn’t necessarily mean a plane designed entirely be civil servants would be better.

That is correct, you get some sort of mix or grey area. I think there was an interview with some of the engineers with an airplane manufacturer that described the changes after a merger where both companies were general commercial companies with profit in mind (and shareholders etc) but one had a company culture of doing it right and the other wanted to lower that down to 'right enough' hoping to make a bit more money that they didn't actually need on top of the billions of profit. But that's what minmaxing with do...

That’s way too simplistic. Antonovs when they were ‘public’ Also had problems. Being public doesn’t immunize them against cost-benefit decisions.

Have you seen early aviation, before the government put all the regulations in?

There is more to it. Usually people don’t like to take plane from airline if they have a lot of accident.

If i build a bridge and it collapse, how I’m making money now? If I have other bridges, people might stop using them if they are known to collapse and kill people.

Unless of course they need to get from point A to point B and you have a mono(duo,oligo)poly on bridges on river C flowing between them.