Non Jews can live in these areas too - I've read about there being a bit of conflict between the ultra orthodox (UO) communities and their non Jewish neighbours. At the height of lockdown last year, there were videos going round of mass gatherings of UO Jews in one of the New York boroughs. Unfortunately a lot of these people believe god will save them from COVID and wouldn't let lockdown disturb their lifestyle. They put the mitzvah (good deed) of mass prayer over the mitzvah of preserving life. I think their neighbours have every right to be annoyed at this as the UO Jews make up a good proportion of these neighbourhoods and if they were all disobeying lockdown rules, it can have a big effect on the cases in that particular area. Unfortunately like with every protest involving jews, there is going to be antisemitism involved which is obviously horrific. I live in a very Jewish area of Manchester and we had to have posters on the street to remind even modern orthodox jews that the covid rules still applied to them and that they couldn't just go about as they pleased just because the bible states that prayer in groups needs to take place multiple times a day.
We do have similar areas in the UK, just on a much smaller scale. Manchester and London have the highest Jewish population in the country so you'd most likely see UO jews walking around in the Jewish areas of those cities. They have very particular clothing - the men wear big fluffy hats and often tuck their trousers into their socks for some biblical reason that I have no idea about so you'd recognise them straight away. You might have to dig deeper into the neighbourhoods though as they often keep themselves to themselves and wouldn't venture out to big shopping centres or anything with too strong of a secular influence. The worldwide population of jews is so small anyway so the number of UO jews in the world is so so tiny. I think most of them reside in Israel or New York.
Julia seems to be rebelling because of how oppressed was in Monsey. I don't think they could legally kick her out of the supermarket for wearing what she wears but she would definitely get a lot of stares. I'm quite secular myself and don't believe in women having to dress 'modestly' for the sake of men ever whether it be because of the bible or slut shaming etc but if I were to go to the jewish supermarkets in my area, I wouldn't turn up in denim shorts and a crop top. I wasn't brought up being made to dress in colourless thermals all year round to not tempt men but because Julia was, its like she's proving to the people of Monsey that she can do what she wants and that she thinks modesty rules are a load of BS when she goes back to the area. If she wasn't tied to Monsey because of her son, I doubt she'd be back there often at all. She's lucky that she can go back whenever she pleases as some who leave the community are forced to cut ties altogether and never come back because of the shame they've brought on their families.
UO judaism is so odd to me as a jewish person myself who had a jewish education for 15 years so I can't even imagine having to get my head round it as a non jew
I've been taught by rabbis who think UO judaism is batshit crazy but have wives who wear wigs and would never wear trousers which is ironic.