You're Way Off Base Nick
An industrial geologist would be familiar with the actual concentrations at which we mine oil and gas which are far higher than 2%. The global concentration of a chemical is irrelevant to whether or not it is a practical resource. The point of the article is that even local concentrations are small. Perhaps I was over generalizing but the data seem to indicate this stuff is highly dispersed so I was assuming the 2% number was pretty close to the highest the local concentrations. I wasn't even saying 2% was impractical, just far less practical and/or far more difficult to mine than Martian water.
Regards,
Mark