Are you suggesting that folk music is only folk music if it is sung by the poorest and least educated people in the society? To suggest that instruments were rare as they were expensive is rubbish. (It's like suggesting that cars are rare as hardly anyone can afford a Ferrari!) Okay, they wouldn't have had professionally built violins and flutes but many people are very capable of knocking up some sort of instrument from the materials they have available to them.

Bob Copper said that his father used to sing in time with his hammer whilst mending shoes and boots and I'm sure many others did too at their various occupations. So yes they were accompanied.

Whilst the point above about the freedom singers used in phrasing and rythmical changes making accompaniament difficult is true, many, if not all, popular songs of the time WERE written 'musically' and only later would the singers have varied the tempo, rythmn etc to add interest to the song when it wasn't accompanied.