As far as the legacy carriers are concerned, prices have fallen more or less constantly over the last 20 years, the easiest way to track them is in revenue per kilometre, which is a statistic which is not difficult to find (on an indistry basis). Sure, it's not benevolence but driven by the LoCos.
So no, it's not 'cut costs and pass the benefits on to the customer', it's 'cut fares and do whatever is necessary to get the costs down to match'.
Oh dear, I started a sentence with 'so'. So sorry.