>What is the proof for that, especially considering events like Ariane 5?

Ariane 5 is a nice anti-ada catchphrase, but ada is probably the most used language for war machines in the United States.

now the argument can be whether or not the US military is superior to X; but the fact that the largest military in the world is filled to the brim with warmachines running ada code is testament itself to the effectiveness of the language/dod/grant structure around the language.

would it be better off in c++? I don't know about that one way or the other , but it's silly pretend ada isn't successful.

But Ada had for a number of years a mandate to require its usage [0]. That should have been an extreme competitive advantage. And even then, C++ is still used these days for some US military projects, like F-35. Though I don't know whether the F-35 is successful or not, if it is not, that could be an argument against C++.

Ada is almost non-existent outside its niche.

The main companies arguing for Ada appear to be the ones selling Ada services, meaning they have a horse in the race.

I barely have any experience at all with Ada. My main impression is that it, like C++, is very old.

[0]: https://www.militaryaerospace.com/communications/article/167...

> The Defense Department`s chief of computers, Emmett Paige Jr., is recommending a rescission of the DOD`s mandate to use the Ada programming language for real-time, mission-critical weapons and information systems.