I have a 2010 Prius and never added any oil between oil changes until about 90,000 miles. At that point my Prius started using oil and now I add about 5 quarts between the recommended 10,000 mile oil changes. I am currently at 115K miles. Toyota acts as if this is normal and no problem exists. I have never heard of a car burning oil at this rate, and why would one have a 10k mile oil change interval as when the oil pressure light goes on you run the risk of engine damage and a potential engine seizure.
Toyota needs to step up and fix the problem. I was a big advocate for the Prius, however unless Toyota steps up to correct the situation I will not be replacing with any Toyota products. I currently have all Toyota (Prius and a Highlander).