They probably don't have whole lot of choice.
There are probably a handful of them who can 'evangelise' about clothes and style and godliness, e.g the pastor's wife, howeve I guess a sizeable number would be longing to blend in and wear a pair of jeans/trainers/smart top/have a crop hairstyle etc.
Lots of these religious groups don't allow women to wear trousers, have their hair cut, wear makeup etc and as I said I'm quite sure many of them don't exactly love the way they look.