Not true.
You have to be very careful playing, or singing, Happy Birthday in any public venue. The song is under copyright, and the rights owners often enforce them.
I think this is known by most people who make their living in the music business.
In June 2013, a film company working on a documentary about "Happy Birthday to You" filed a class action lawsuit which seeks to invalidate Warner/Chappell's claim to copyright ownership of the song and force the company to return millions of dollars they have collected over the years for wrongfully asserting copyright owership. But that case has not been fully adjudicated, and unless and until a court invalidates Warner/Chappell's assertion of copyright ownership, the song "Happy Birthday to You" remains in a copyright-protected state. Read more at http://www.snopes.com/music/songs/birthday.asp#lpyagJuFPYWhdJ51.99
I think this is known by most people who make their living in the music business.
Why not raid kids’ birthday parties?