Software has n^2 as many paths a piece of code can take depending on how it branches. Also, you cannot simulate the rest of the world (externalities).

If I design a bracket for a TV mount, do you blame the bracket when someone hangs a 3000 kg bookcase on it?

You’re expect software to be perfect, yet ignore the massive limits everything in the world has.

Not saying there aren’t quality issues with software. I’m saying software development is really difficult.