I checked the plustalk rates to Turkey: 15p/min. I can call for 1p/min to fixed lines in Turkey with dialaround number. For mobile phones, I could call for 5p/min. Something is wrong with plustalk's prices.
Not necessarily - different service providers are able to provide different pricing. Perhaps Plustalk are unable to offer an attractive rate in comparison with others because of some commercial arrangements with a carrier along the routing.
On many routes, Plustalk's pricing is very reasonable.