It sounds like you're not asking about technical enforcement — as opposed to prodding, which is what I was talking about. You're right, though, they do also app

It sounds like you're not asking about technical enforcement — as opposed to prodding, which is what I was talking about. You're right, though, they do also apply pressure through technical means. They did this at design time, by thinking through what the default QoS will be when it is left unspecified.