If they're not superhuman then why do they sign up for the job?

Personally I don't remember nor plan doing #1 and #4 seems directly linked to it. Since #4 is the essence of their job, fixing it would most likely fix a great deal of #1, that means if they actually did what we pay them for then there wouldn't be as much of a need to lie.
Or in other words if you paid someone to fix your toilet and he still didn't get the job done after two years, would you keep paying him and say he's alright?