the ghettoisation happens because there's a big variety of price/quality combinations for each type of business.
in an affluent area (where house prices are enormous) the local offering includes cocktail bars, bijou little independent stores, delicatessens, artisan bakers and organic grocers, interesting cuisine restaurants and various businesses aimed at capturing the wallet of the wealthy locals, but the people who work in these businesses will generally not be able to afford to live locally and probably can't afford to do all their shopping there either, and there are also a lot of people who culturally and for preference want to be able to spend their leisure and shopping time in such areas but can't afford to live there.
The more affordable areas don't have such shopping areas because the local population in general can't sustain them - they've got a "local value" convenience store, a fish&chip shop, a barber and a vape store, with an aldi/morrison low cost supermarket and a pharmacy a short drive away on the ring road. but a significant minority of the people living there would have loved to be able to live in one of the posh areas, and may even have a job there, but they are living where they can afford to live.
making the lovely area into a pedestrianised low traffic zone excludes all the people who can't afford to live within 15 minutes walk, or who like to stop by there on their way from affordable suburb to different suburb where they work.
gentrifying all these hinterland suburbs isn't a solution - the low budget options are needed by a large proportion of the local population, but don't meet the needs of a significant proportion of those living there, who want a different quality/price point for their goods and services. but while the population of a single zone will be variable, the economics of pricing and market for each business mean you simply can't put a low-budget version and a posh version of the same kind of business on the same street and let both attract their own customers from among the local population, it doesn't work like that. The low budget version goes in the poorer area and the posh version goes in the posh area, but people can move freely and go to where the businesses they want to use are located.
all the pilot schemes are about making it more difficult to use the lovely areas if you aren't lucky enough to live nearby, but the problem about how to give access to the same kinds of spending and working opportunities to those who would otherwise be driving to those areas regularly (but are now being prevented) isn't being addressed, because there isn't really a workable solution so it's easiest to just ignore it and focus on how much lovelier the lovely area is now that you can hear the birdsong rather than the streets being lined with the parked cars of those who you have now excluded.