if i am a child, with no money, or am un- or underemployed with very little money in the form of disposable income, then this advice is not actually actionable.
not to mention that it is also wrong - you do not owe the street performer anything, no matter how long you stop and listen for. they are not entitled to anything just because they made a choice to perform in a public place. and this is not to suggest i have never, or will not in future, donate to buskers etc. - but it is always an active choice...