Why are academics using Google Earth imagery instead of…

I was totally into yesterday’s NPR story about a group of researchers in walking the route of a new road from a remote village to the big city of Iquitos. It was all rough terrain and jungle and the idea was to explore the impact of the road on deforestation and human health, including the spread of malaria. The one statement that stopped me dead:

Pan has brought the only maps they have — Google Earth photos from 2003.

Later researcher Pan notes:

“I learned that the parts of the road that look on the satellite image as cleared are actually not as cleared as it appears. And there’s not as many communities as we had thought there might be.”

I have what are perhaps naive questions. Surely there are newer images available? Why then are they using old images from four years ago? Is there no funding to acquire newer imagery? If there is no or little funding did the researchers at least ask for a break on price from commercial providers?