Nothing to stop them flagging users though, that doesn't actually mean anything as a term without more detail. Every ISP I've worked for has recorded usage data in various levels of detail and unusually heavy users are identified as a matter of routine - that's entirely separate from whether they have traffic management and whether they use the usage data to seed the traffic management though.
I have a list of our current top25 users on one of my screens right this second, if people remain there too long they generally attract my wrath (though usually because it turns out they're compromised in some way and sending vast amounts of spam).
