>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.