Community care/nursing staff sometimes have no choice but to wear uniform out, they may be collecting a prescription or shopping for their service users.
Yes you are supposed to cover up but a uniform is still going to be obvious under a cardigan worn in warm weather.
With regards to uniform transferring pathogens, PHE does not agree, most recent guidance states:
'It is best practice to change into and out of uniforms at work and not wear them when travelling. This is based on public perception rather than evidence of an infection risk. This does not apply to community health workers who are required to travel between patients in the same uniform'
So perhaps some people should stop being so instantly judgemental.