It rarely changes the opinions of the current generation but it can have an effect on the next.

I think the difference is that one simply means some people lose social opportunities and the other creates a society that actively cripples many people for being different.

I was told this story a long time ago in Hebrew School... it may or may not be a Bible story or some tradition passed on in commentary. I have no idea of its truth value, nor do I really care, because it has a lot of power as a story. I think the context I was given was why God punished and/or destroyed these people.

There was a town that would let any people come to it that wanted to. And if the people asked for help, the people would give them money, but they'd give them special marked coins that meant they were outsiders. None of the people would take that money to give them food or shelter. None of the people would give them food or shelter out of charity or kindness. As a result, people would travel to the town, not realizing that they had no ability to again basic resources like water and food, and the visiters would die. One day a child of that town took pity on a child who was with someone traveling and brought the foreign child a jug of water. The local child was punished by being stripped, tied to a tree, covered in honey, and left to be devoured alive by ants. I think it's the latter part that helped me vividly remember the story. This was the final straw, and God destroyed these people, because they were inhospitable, which is a very, very grave sin. Plus their conspiracy of not being willing to trade with outsiders, plus their lack of openness about it, was tantamount to murder.

If you allow systematic prejudice, you will get regions where people in certain minorities cannot acquire necessities. You will get regions that simply won't assist some people. And then you create nightmare scenarios. It may suck to not get invited over to dinner, but you're not being denied the ability to buy groceries or gas so you can leave town.

I can't help being amused by this question. I know this question is specifically for this issue and British society in particular, but I think the question was definitively answered by the civil rights movement in the US (and for the US) for a different host of discriminatory 'traditions.' Boycotting played its part in moral suasion (with little larger financial impact, when the market was already profiting from an apartheid system that had traveling bluesmen sleeping in their cars or bus stations, not hotels), but ultimately corrective legislation was required.

Well, given the choice between legislating a social norm to allow minorities to hire a room at market price from a hotelier like any other customer, or a police state to keep order on a restive population well down the cycle of violence - the decision was clear.

As I said, this was clearly the state of US society at the time.

Incidentally, none too dissimilar extremes played out in the Castro after the Harvey Milk murder trial.