Wouldn't he only be lazy if he's not doing anything else more productive instead?
He gets payed to do a specific job, and does it the best way possible given the constraints. I don't see how you find lazyness in that.
The customer simply isn't willing to pay the extra time for it to be optimized, and he ain't doing it for free.
I don't know which job you do, but do you spend a lot of voluntary overtime just to do things the customer isn't even asking or paying for just because you think it's better?