Yes Marrianna , there's loads of cases of people not being rewarded for ideas (intellectual ideas) .....even with a patent ,it costs a fortune to prove you are the original creator....and so it is with songs....someones not likely to rip you off in black and white, so you have to employ experts to do it for you,,,,very expensive..
actually a friend of mine told me years ago his brother sent Elton John a song called 'Friday nights alright for fighting'..and EJ released 'Saturday night is alright for fighting' ..........i myself sent a lyric to a duo,who put a song on an album with the same theme!..so, there you go.