Fast charging is already expensive (often moreso than fuel unfortunately). The idea being proposed here is that if you make it slower, people get hungry and you can sell them more junk food. You lose that opportunity when charging is too fast, most people get their petrol and drive on instead of getting food each and every time. So it's actually better to have slower charging, even if you can then charge less money for the energy itself, since you have a captive audience.

Charging at public chargers in UK is insane. £40+ for a charge.

I think their point is that for a business a captive audience is a good thing. Kind of like how some grocery stores have noticed that when checkout takes longer, people are more likely to buy the drinks and snacks they put for sale near the checkout line. Likewise a charging station could have an overpriced restraunt selling low quality burgers for twice the price of the restraunts 2 minutes away by car, and customers will eat there because, they don't want to sit around for 30 minutes, and then drive down the road and stop for another 10.

Unless I'm missing something and fast chargers charge by the watt instead of the hour, in which case that's pretty big BS.