Work on a massive decades old software project and get ready to have your eyes opened. All the automated static and dynamic software analyzers catch only the easiest flaws, but can catch the more serious ones only if you're skilled and lucky.

Firing people for software bugs is the stupidest thing I've heard in a while. Everyone writes horrific software flaws. Everyone. The best of the best programmers just write less of them. Firing people for bugs is a job perk that will only motivate any good developers to find a less stupid employer as soon as possible.