When selecting the flight through Kayak, it says it has included price for seating and carry on baggage. Until the booking is complete, it will not say that the prices has to be paid again at the airlines. Once booking is complete it says that we do not collect baggage or any other fees that is part of the airlines.
The price charged by the JustFly for the ticket is more than the airlines provide at their site. If you are in a hurry, this is what happens and they take advantage of the people in hurry and a very bad predator model in the airlines booking. I am not sure why they are still kept in the business.