This may be untrue. Perhaps they really do just have a song in their heart and don't care what other people think of them. There is someone singing in the hall right now and she is annoying the hell out of me. She's actually got a fine voice, but that isn't the point, because I don't want to hear her sing right now. If I wanted to hear her sing, I would have asked.
But if she and others like her really don't care what others think, maybe they should. Maybe they should consider that, by singing out loud and in front of everyone, they are invading everyone's space. Some intrusions into personal space are expected and unavoidable and are a part of life. But singing in public is different. To me, singing in public is like smoking: both fill the air with an unwanted pollutant. There is a reason that people get such joy out of singing in the shower or singing in their car - it is precisely because singing aloud is something that does not happen often. Just like jumping on a hotel bed or drinking milk from the carton, it is a joy that is not always allowed.
It makes me sad to write this, since singing is such a cheerful and happy activity and I am the joyless grump who wants them to just shut the hell up. So I will close with a self-directed rebuke by Robert Frost.
A Minor Bird
I have wished a bird would fly away,
And not sing by my house all day;
Have clapped my hands at him from the door
When it seemed as if I could bear no more.
The fault must partly have been in me.
The bird was not to blame for his key.
And of course there must be something wrong
In wanting to silence any song