Yeah, as you correctly point out this is not City's (or football's) problem to solve alone. Racism is a societal issue and while things are getting better in general, racist attitudes have been getting more visible, and -- I'd like to say "popular" but I think saying "safe to display in public" would be more accurate -- recently, largely thanks to the rise of right wing politicians everywhere in the world. This doesn't mean the fight is hopeless, or shouldn't be fought. Ban people when they do racist things, give clubs meaningful penalties when large scale racism occurs (instead of fines, deduct points. Supporters in the stands don't give a feck if some anonymous millionaire is out £50 000 but will start to give a feck if their club loses points due to racists, which leads to my next point), and also do community policing. When you see racism, if you can, call it out, even if it's a United supporter. Nobody has to fight people in the streets, but for instance we've had plenty of questionable views and opinions expressed here, and it's important to call these out when they pop up. Let them know their views are not welcome.
Beyond that, outreach and education. I am very proud of United for taking a public stand to support charities and organizations like Stonewall, and for the "All Red, All Equal" campaign. It might not make existing bigots change their views, but maybe it will reach the next generation and teach them from a young age that everyone is equally important and valued. Maybe when someone sees a player they support and like come out and share stories of abuse they've suffered or to condemn racism, they will rethink their attitudes. Maybe not, but hopefully some will, and that's a step in the right direction.
Ultimately, give people the opportunity to change and to make amendments. When I was younger, I was a very angry young man (I was really angry and disappointed about my life, but since admitting that is very hard, I was focusing on easier targets) and got convinced by some very presentable and fancy-talking racists. Luckily I never abused anyone, but I did hold a lot of views I now find abhorrent and for me it took exposure to people who were a lot smarter than I was before I started questioning my views and opinions, and took a long and hard look at myself. Change can happen, even if it doesn't happen overnight, but if we slam the door on people, they will just drift further into more extreme groups and views.
