For me, I just hate standing in a queue for long periods of time. Also, in my town, queues can get up to ober an hour in security, propmpting peeple to potentially miss their flight or planes being delayed.
I’m guessing it’s the “peak dates” thing. They have a base price aka. minimum price when planes are mostly empty and then put on a surcharge for when demand is high, instead of altering the base price.