The most trivial software system you can think of nowadays is already so large in scope and/or complex that you can’t prove it doesn’t work either, because ther

The most trivial software system you can think of nowadays is already so large in scope and/or complex that you can’t prove it doesn’t work either, because there’s no complete specification on how it’s supposed to work - if it existed, it would be the bug-free software itself, because all software is specification. In the end all that matters is whether the system is useful, in an economical sense (value delivered > defects over time). So I would argue software did not get reliable, our bar for defects remained low, but the relative value delivered increased a lot because software has amazing leverage.