I live in a neighborhood where the median income is below the national average by about 10% and above the national average by about the same amount. This implies to me that there are is a fair bit of economic diversity.
Also, I very rarely encounter a service worker that does not live within 25 minutes of the establishments in my neighborhood unless they do so by choice to live in a much hipper neighborhood.
Part of this is a university that stabilizes the real estate prices and attracts a lot of low income students who take on service jobs, but also a big part of it is housing diversity. Within 1 block of me are a commercial district, a high rise building, many mid-rise buildings, lots of townhomes and a handful of single family homes including at least 2 I’d call mansions. This housing diversity came about due to several phases over the course of over 100 years of urban planning that specifically centered on making it possible for lots of housing desires to be fulfilled in a single place.
It’s entirely possible if there is enough will. But that will is lacking.