Speaking as someone who was recently in hospital for a long period as an inpatient, it was absolutely crucial to get to know the colours the staff were wearing and what they mean.
The NHS is very hierarchical and specialised - so if you wanted to get your medications sorted, it was crucial you were speaking to the nurse, because eg a health care assistant wasn't going to know and wouldn't necessarily pass your query on. If you needed someone to eg change your bedding, you would probably mortally offend someone higher up the food chain than a healthcare assistant if you asked them to do this (and they wouldn't do it).
The doctors not wearing any kind of uniform or identifying badge is also a real issue, because often the junior doctors are very young and frankly look no different to a health care assistant (some of them wear scrubs too). But of course it's really important to know if the person giving you medical advice is actually a doctor. IMO, doctors should wear an easily recognisable uniform too. But if course they won't, because they currently get to wear whatever they like (hygiene rules don't seem to apply to doctors for some reason?), and can't see them wanting to change that.