Until people stop shopping there, I can't see much changing. People on this forum are almost certainly going to be shopping around, but a lot of people won't want to leave a station. They're nervous enough navigating their way around the station itself than getting lost outside. Then you have the people who turn up last minute and wouldn't even have time to shop around.
Someone is buying those stupidly overpriced bags of Haribo from WH Smith or else they'd cut the price!
It's the same in supermarkets. They argue they're not profiteering, but we now see in the US companies like Kraft Heinz talking of increased profits on lower volumes of sales. Firms are bragging to shareholders how they've managed to price gouge in a time of economic instability, and we only need to look at oil firms who reduced supply to get prices up and have ALL made record profits in the last year.
I have little faith in regulators and Government, who drag their heels. Even when they know something is bad, they take their sweet time to allow businesses to make as much as possible for 'the game is up' and by then, they'll have found another way to make money and the authorities will move at a glacial pace once more - perhaps even delaying legislation because there are supposedly more important things to worry about right now.
So once again, who has the power to change things? You and I. We stop shopping at certain places, or stop buying specific products, and we can make a difference.. but I don't see any evidence of that at stations or airports. I don't often visit motorway services but when I do, I have to say that WH Smith seems pretty quiet compared to years gone by, but everyone is happy to spend money on a Costa.