It's my guess that Olympic only offer transfers as included when they are using their own designated airline, Enter Air seem to be the ones at the moment, but, as you know, Germania were used as well as others (remember Monarch!)
Enter Air do not appear to be used all season, certainly not early or late, and, if the flight used is not Enter Air, but someone like Thomas Cook, Thomson or Easyjet, then the transfers are extra.
We went to Kalamata in June, and Olympic use Thomas Cook if you book before Easyjet release their schedules for the month in question, but, as soon as Easyjet flights can be booked, then they really only offer Easyjet as that is the most cost effective. We are waiting to book Kalamata again for 2017, but Olympic only offer Sunday flights using Thomas Cook, and the cost is sky high, we have to wait until September or Even October before the Easyjet release of flights, and then we can book for any of several days of the week, 7/10/11 holidays, and at a price that makes sense!
We are in Plakias in October, and again Olympic use Easyjet as the last Enter Air flight is 4th. October. I must say that June was our first ever Easyjet flight, and it was probably the best short haul flight we have been on. Self service check in, booked seat numbers, on time, and comfortable!
Roll on October - an early flight, zoom through Iraklion airport ?!!!!? booked taxi with Zacharias, so we expect to be supping our first beer (is it still Alfa?) with Angelo and Kostas for a slightly late lunch time.