It takes longer to make the foods of where I think you're imagining and it is more expensive when doing it properly - this is just a general reason for inconsistences of quality and access, and why it'd be more difficult to stay in business even in bigger towns and cities.

Secondly, colonial history and of where people of the "commonwealth" would settle after coming.

Equity to open.

Racism and hierarchy of race in the white supremacist structure. It's well documented Black people in the UK were some of the least likely to be granted loans to be able to try business ventures.

Anyway, back to the 1st matter, the foods I think you're imagining, to make them at their peak actually it takes a lot of work and expensive ingredients. There is even party versions, home versions, and restaurant versions of some foods. That means they may have more range of seasoning, cooking technique or even less proteins or ingredients apart from the staples and 1 protein etc.

Finding the chefs and cooks for the labour of it means in small towns you're basically looking at a family affair or you convince the few other people from your country or close enough culture to abandon their existing job to bank on mostly white English people to accept the traditional foods when even Chinese and Indian foods have dishes which to me are absolutely vanilla but to others are "scary". HK chefs in the 60s and 70s abandoned many delicious recipes because the locals simply wouldn't do it.

So with that, most of them are cooks and not chefs who create dishes, do the RD for making home dishes more "appealing" is a lot of work and another skill. For example, if it was any of the western African dishes that use leaves or okra that become slimy, would they decide to start adding tomato into those dishes so the sliminess is reduced significantly?

Most African restaurants in London focus on appealing to people from their home countries and neighbours who understand, then whoever joins in is a bonus.

British people who aren't from those backgrounds need to take a plunge.

Lastly, in smaller towns it's more likely that there is an auntie selling food but she does it via WhatsApp and you just have to make friends with more diverse group of people to find out. Usually they'd be attending the same church or the 1/2 salons there to find out about it.

For food from the islands, specific groups dominate in the UK and also once again, ingredients can get expensive and cooking techniques can make it a much tighter operation. But others can correct me on that, that's just an assumption based on the different foods I've seen around and watched prepared on YouTube. For me, I found the humourous "we nah 'av dat" jokes from Jamaican restaurants was because it takes so long to make them that when it's out, it's out for the day.