Most of the trivial questions, i.e. the questions answered directly from Google, get the most upvotes when answered. Take for example this question:
The answers get many upvotes, while they are directly quoted from the first Google hit.
On the other hand some answers that took the answerer great time to think about and write never get an upvote, if they do then its 1 or 2 upvotes.
Most people tend to hunt for simple questions and answer them very quickly, there should be a motivation to make people answer hard and old questions.