@MarsC,
I suspect that CPU, being the corporate behemoth that it is, has a few layers of managers whose job it is to manage other managers and this will go some way to explaining the counter-intuitive margin differential between it and ASW.
AS to CPU's genesis and how it got to where it is today... CPU owes its existence to developments in the 1980s, when companies - who until then did everything in-house, including managing their share registers - discovered the joys of outsourcing the things they did not like to do or were not good at doing.
CPU was a first mover in responding to the demand for registry management.
It is quite a success story, having grown organically for many years from day 1 (which was pre-1980, I recall). Where CPU started to run aground to some extent was when it embarked on an international foray commencing in the late 1990's, and then in the 2000's it began acquiring not only registry business, but all manner of different businesses that it claims are tangential to the business model of registry services. Me, I'm not so sure.
But what I take away from the CPU story is, as I have argued earlier, that incumbency in this industry counts for a lot.
That CPU has been around for almost 40 years, and the other registry companies have also been in profitable existence for periods measured in decades, provides some insight into the durability of the business, I think.
Especially when you think of the various generations of technological change that these companies would have seen come and go.
Based on quite along precedent, and at the risk of displaying a blindly-optimistic, MSB-esque mindset, I'm more inclined to think that technological disruption, rather than torpedo the current operators, is what keeps them ahead of any wannabe competitors. That's what history suggests, anyway.