The money is taxable. Any money or other goods/services received for a thing or personal service is taxable. That doesn’t mean a return automatically must be filed. AGI has to be more than the standard deduction to have to even file. There are exceptions which make you file even if no tax liability.
Under U.S. law, gifts aren’t taxable income to recipients. A panhandler asks for money and receives some from kindly people, without providing any goods or services as consideration. That money is a gift.