I think it's also about the British attitude of not asking, and not bartering.
Every year or other year (depending on contract length) for maybe 15 years my broadband provider has tried to put up my broadband by a silly amount. Call up, and they always manage to bring it back down, often to exactly what it was before, which is a real-terms cut. In fact the same is usually true for new customers.
You can bargain in shops, including supermarkets. I've done some very large shops for events before now and supervisors or managers have managed to apply up to 10% discounts. I've had discounts from Tesco, Currys, Staples, Argos off the top of my head, just by asking.
The same goes for airlines. A few years ago I was travelling back from a funeral, after which, after a series of trains owing to its remote location, I was shattered. When the checkin counter attendant asked how I was I was maybe a bit too honest that I felt like crap, and why! I wasn't fishing for anything, I was just tired and mentally dumped it on her a bit when asked. Anyway, she upgraded me to business, which meant I could at least get a lie-down bed instead of an upright seat and have a chance of sleeping. It was massively appreciated.
Of course, there's a tone to this as well, including when making complaints/grievances. The person in front of you dealing with your refund request in a supermarket when you've forgotten your receipt is following policy. You might find a way of getting around that policy with supervisor or manager discretion, but not if you start kicking off demanding things.