Perhaps we are luckier in the UK than some areas and though there are the festivals with multiple amplified stages there are also lots of
smaller fests with only a main concert stage and a dance area PA'd
up.and space allowed usually in a local hostelry for informal song and
instrumental sessions.And at the larger festivals there are usually places close to the main site where informal fringe activities happen.
Look at Sidmouth and the number of widely varied pub sessions that go on there.