This isn't Afghanistan, people can wear what they want
No they really can't, at least not in public spaces, or in other people's privately owned spaces. Plenty of businesses have dress codes and refuse admittance or service on the grounds of that code. It's a shame that some people don't seem to understand that now, hence Tesco,eg, having to actually specify 'no pyjamas', but there you go. It would appear some people are a bit thick, and/or think that rules just don't apply to them.