There are times that imagery can be used from those sources and as an individual for personal use you typically can do that. The problem becomes with licensing for businesses like us. We do have to adhere to specific mapping licenses to show and print the imagery we show. For businesses, places like Google or Bing have very specific rules regarding selling and distribution of imagery data. We are in the works of adding other sources like they use rest assured.
If you do find that an image you see somewhere else is what you would like, let us know directly and we will try to figure out a solution for you. Use the Contact Us page for these requests.