This makes no sense. A solo traveler can decide to take a trip because they saw a good fare very trivially: you're not going on a trip with 2 days notice just

This makes no sense. A solo traveler can decide to take a trip because they saw a good fare very trivially: you're not going on a trip with 2 days notice just because a fare "tipped the scale" when you need 10x the planning and logistics, and the airlines know that. They're not doing it to entice families to travel, they just know solo travel is associated with higher incomes and want to extract more money.