Does public art have any artistic value or is it just a social statement?

If art is on the street, not in a gallery does it have a different outcome? Do people looking at it have a different perception? Is it only art if it makes a profit – or is it about the personal journey, both for the artist and the viewer? Is it art if nobody is there to see it? Is art still about the talent of the artist or has it become about understanding what the market wants – and how to make money? Is consumerism killing original thought, or just forcing artists to approach it from a new angle?