This sums it up nicely.

Also, if it's easy and you've done it a million times, charge an inflated fixed price. If it's new territory, charge by the hour.

Edit: before I forget, if you let them know how it's done then you need to charge for the several times they won't come back again afterwards.

Bingo. Besides, people are scared by humans capable of doing tasks much faster than previously thought. When in doubt, sandbag!

See also: the scene in the film "Big" when grown-up Josh Baskin (Tom Hanks) gets the lecture from a Co-Worker (Jon Lovitz) to slow down his data entry as to not get everybody fired by going at a leisurely pace.

The weird thing is, this was a very small business who hit the jackpot of high Google ratings. They weren't a heaving bureaucratic business.