in my opinion the big difference and problem is that space and resources are virtually unlimited, and a "product" can keep changing indefinitely too. and if something fails, in most cases it will fail very differently than in other engineering disciplines. I agree it would be great to write more prototypes and all that, but hey, capitalism: good_enough/shitty makes money, so that's where we are (also, CS is rather new, we are still figuring out a lot of things, still getting deep in the mess)