We revisit thirty-five years of history related to the design of Quality of Service (QoS) on the Internet, hoping to offer some clarity to current debates around service differentiation. We describe the continual failure to get QoS capabilities deployed on the public Internet, including the technical challenges of the 1980s and 1990s, the business challenges of the 1990s and 2000s, and recent regulatory challenges. In short, while the standards community developed protocols to support enhanced services (QoS), service providers have only deployed them in intranet scenarios where they can internalize costs and benefits, rather than across fiscally distinct organizational boundaries. We examine lessons learned from this failure to deploy interdomain QoS, the resulting tensions and risks, and their regulatory implications.