So, when you produce the acceptable code faster you can go home earlier? No more work in a week? If not, you are paid by the hour, you just wish you would be paid for producing acceptable code by the deadline (me too btw).

Yes, technically I could. But in reality, I have more than one task on my plate and a well-managed company will have figured out how to set the deadlines to maximize the amount of work they get for their money.

However, this is one of the things I ask about when I'm interviewing for a position -- if the company keeps track of hours rather than paying for work product, then it's not likely to be a good fit for me. So, my experience is not random chance and may not be representative of the industry as a whole.