Originally posted by Delta 62
Well first off..because they DIDN'T drop Yoda off. He chose his exile himself and arrived in one of those escape pod things he left Kashyyyk on. Only Obi knows where he went. And do we actually know Artoo knew who Yoda was by word of mouth? There was no way Luke or Yoda could've known what Artoo was saying on Dagobah, he wasn't plugged into a translator. It's one of the great mysteries of the world why Artoo chose to remain silent on EVERYTHING.
There's an interesting article on Cracked.com - a fan hypothesis that both R2 & Chewbacca are both spies for the Rebellion movement, and don't share information. It's 'Films Improved by fan theories.'