They may require booking by a certain time, although travel may commence later. The lowest prices may be only for certain days or times of day. For example, midweek departures are less popular than Friday and weekend departures, so midweek may be on special. In addition, the provider may find it necessary to change the details of the offer, so they always allow themselves this option. A number of taxes and fees are not included in some packages, especially cruise packages.
Examples are port charges and fees.
Many vacation packages do include all fees and even transportation to and from the airport at the destination, so make sure you understand what the total price will be before you agree to purchase. The assumption that is made for travel packages is that the accommodations will be occupied by two people. For a cruise or a land package, air may or may not be included. Make sure you understand what is included in the price and how much more you will have to pay for the extras. Sometimes breakfast is included in a hotel or resort price.