My singing partner, Margaret Nelson, busked a couple summers in Chicago. There, you need to pay for a buskers license. There's no question of the city paying you anything, it is all tips from passers by. She found that she did better if she dressed up (look like a beggar, you get paid like a beggar she says) and did fairly well. Being a singer, she was only able to keep it up for two hours at a time. Did the best at farmers markets.