Take for example the lag bug. How many hundreds if not thousands lines of code is there to check to see what is causing it (even looking g for one single character that is incorrect)?

Once you isolate it, fix it, how many more tests do you have to run to ensure it is not screwing something else up somewhere else. And if you find out other thing out of wack.. fix that. I am sure it would be like wack-a-mole.

I am no coder, but I doubt this is something that part time coders could isolate and then fix as easy as you make it sound.