As the title says, one of the lessor obvious revenue methods is to allow you to sit with your kids IF your willing to pay extra to do so. As we know, some airlines like American Airlines, Allegiant Air, and Spirit Airlines charge for virtually every seat reservation on the plane, even if you’re in economy class. And, the issue is not so much whether the airlines should (or can) be charging for economy-class seat reservations since they technically have the right to, the issue is that for parents, in the end, they are paying extra to sit with their own kids under these allowable rules. And it happens because airlines reservation systems are not optimized to keep traveling families together; they’re programmed mostly to eek more revenue out of their passengers where possible. In doing so, they logically break up the traveling family and the only way to put them back together is to pay extra to get a block of seats together or move (up) into a class of seating that has a block of seats together. And thus, more revenue generated by you wanting to keep your family together.