I also wouldn't be surprised if Apple employees tended to test on the newer Apple gear, and older models sat somewhere as part of a bulk testing unit, meaning they don't personally experience the same slowdowns as you.
Indeed. When I was on a six month contract for Retail Software Engineering, I observed that everyone had hardware that was at least a year or two old. I was told that the new hardware is reserved for paying customers, and if you wanted a new machine you could use your employee discount to buy one.
Otherwise, the only people who get the latest hardware are those who need to test or develop code on it, and that is a very small fraction of the total number of employees.