Singing other peoples songs like this for money gains has always been copyright.There is a age limit to where anyone can sing it but i dont know what it is.
In new zealand the local councils charge shop owners or food places if they play music where people can hear it.There is a yearly fee which i presume goes to the artist fund.
It will get to the point where youtube will be deleting all songs or music people are singing or copying because it is actually copyright.The artist owns the song,music and words (phrases) like "another one bites the dust" etc.
If the music industry start to inforce this copyright it will be a sad day indeed.