Why, exactly? I mean, yes, it's written glurgily, but I read the WashPo article when it came out and was struck by how nobody stopped to listen at all.
I don't live in an area where street musicians are commonplace, but there used to be a dude near the University when I worked/attended there who would play around lunchtime a few days a week on the sidewalk near the main strip of hole-in-the-wall eateries. I always dropped a bill or two in his violin case and If I saw him on my way in to lunch, I would make time on my way out to stop and listen for a while. He was talented and the pieces he selected always put a spring in my step. He had crazy, curly, long gray hair and smelled like he slept in a dumpster, but the dude could play like a bat out of hell.
I never got why people would walk by and pretend not to see him, not even drop a quarter in and keep walking. Here's a guy, down on his luck, trying to make a living outside the system by giving something back to the community. Something of value. Something only he could provide -- pouring out his soul on the violin in 100 degree heat on a street corner. I don't know, you gotta respect that, right?