no they can't. it's not possible to write a bug-free application that's 10+ million lines of code. i take it you've never written anything larger than 500 lines so you have no clue what you're talking about
It's very much possible. I take it you've never worked in the nuclear industry, written code for airbag deployment or Space Shuttle guidance systems, systems for ICBM's, etc. so you have no clue what you're talking about.