>On the one hand, this seems fair. If you want to sit together, pay for that privilege. It doesn’t make sense to tax every other passenger for it. OTOH, families are a net benefit to society, so maybe it’s right for everyone else to pitch in a bit. Also, nothing is worse than the folks who didn’t pay up ahead of time who bug one, ‘may we switch seats so we can sit together?’ So perhaps free family seating makes life easier for everyone.

I don't understand, are people buying random tickets and hoping to be put together once on the plane? I've literally only bought assigned seats on flights except on Southwest.

Yes, exactly. They want to avoid the upcharge for seat selection so they roll the dice and hope.