The app only lists the most common names for the fuel types. Those fuel types do go where you saw them. The app cannot know for sure what stations call each of their grades as they may not be standard from region to region or store to store.
As for the prices, yes, that person may have been just posting the prices that were there from days prior without even being there. That is the down side of the award system in the app - it seems to encourage some people to just make up prices for some stations to keep either the top spotter or get a new level of an award. Sadly, nothing is perfect, but you could help fix that by correcting the bad prices. As with anything in life, some people are only concerned about what they can get or not being accurate/focused on details and not in just helping others for the good of the whole community.
That is sort of why I liked the old system when I started in early 2006. You entered prices because you wanted to help others find the cheapest gas and they entered it to help you too. Today, it's more of a game system so many people seem do it more for the awards.
I think people are posting bogus prices just to get on the top spotters list