Once knew a guy from LARP who told a story about when he had first gotten his hands on chainmail and was getting used to wearing it and maintaining mobility and balance with the weight of it (it was heavy stuff). So he started wearing it under his clothes when he was out running errands and stuff to practice for when he had to wear it in mock combat.
Then one night he was coming home late and got mugged by a dude with a knife.
Apparently the look on the dude’s face was amazing when he went in to gut the guy for his wallet and found out he was wearing medieval armor under his hoodie.
So, you know. Pretty good argument for wearing it under streetclothes!