Street music has probably been around as long as there have been streets.
The economics of playing for music next to an open guitar case has an ancient simplicity. There is no middleman, no stockholder, and no investment bank involved in the process; just a pure and direct exchange between artist and audience, and this might be why street music is so important.
Since busking musicians don’t rely on a complicated commercial structure, one would think that they have a lot of freedom to innovate. This turns out to be true; a lot of musical revolutions had their roots on the streets instead of the concert stage - maybe more so before radio and vinyl, but in recent generations also. Folk musicians like Woody Guthrie and Bob Dylan used to pass the hat as did many of the great musicians of San Francisco hippie culture like Janis Joplin and the Grateful Dead.
I think the greatest street music revolution happened in the American Midwest. Country blues musicians from the Mississippi Delta followed the Great Northern Migration and ended up playing places like Maxwell Street in Chicago. Here they needed louder instruments to compete with the noise of the city, so they began using amplifiers. This is the reason Muddy Waters, Bo Diddley, and Howlin’ Wolf electrified the blues and paved the way for rock & roll.
Busking is now legal in Wichita so, in a way, Old Town, is a place akin to Boulder’s Pearl Street, the New York City subway, and Harvard Square in Cambridge. Now we can say we have a downtown cultural center, and maybe even a place in music history.