Let me follow your question with a question. Is that what giving "fast lanes" is going to be about? Actually analyzing the data and determining what it is and what priority it should have? Or is it about seeing where the data comes from and determining whether or not they bought a pass to go faster (or slower).
I have no idea. I'm not discussing fast lanes per se. I'm discussing the concept of equality of data, both in inherent value and as something to be transported. Now, you described two dimensions in which data can be measured in terms of public worth: what it is, and where it comes from. Both can have a huge impact on anyone's perspective as to whether that data should even exist, or if it should be given lower or higher priority over other data. Ultimately, data turns out to be completely relative in worth or value to each person in a given situation. In which case, one cannot claim that such arbitrary worth or value is equal across all possible configurations of data. Hence, you lose the "equality of data", and therein lose the inherent justification behind "treat all data equally".
See in your ideal world, I might agree with you on some level, however those I pay for my access to the internet have shown time and again that is not what they want to do. Why? Because botnets still exist, if it was as easy as saying "oh hey that's a botnet doing malicious stuff coming from 100,000 of our clients, lets just slow that data down to 1kbps and see how it does" then they wouldn't work. Also certain ISPs have shown to cripple services that compete with what they offer. Remember this is about the idea that the internet is an infrastructure, this isn't an argument that "they company should be able to do what they want, it's their lines" and as an infrastructure they should give me access to whatever data that's on the internet without restricting it. So yeah a byte is a byte whether it's the magical cure for AIDS or a video of goats barfing on kids.
So ISPs are supposed to treat all data equally, but in the meantime they should have been getting rid of botnets by...how, exactly? You seem to be confused with what you want. Either they shouldn't be restricting traffic, or...they should be restricting traffic the way you want.
Additionally, pointing out that some ISPs have throttled services is irrelevant. Some have done that, some haven't. Some have caps, some don't. Some offer fiber, some don't. Some have speeds over 50meg, some don't. While competition in the market is certainly limited and incredibly annoying, there's still enough diversity that what you're talking about does not yet affect everyone, or even most customers.