411A:
I am quite familiar with FAA holding pattern crieria. I work with it all the time. There are 31 different templates to fit well over 100 combinations of speed, distance from facility, and altitude.
The FAA folks I work with are the TERPs criteria designers. To assure containment the recommended entries become critical in certain circumstances when jet aircraft elect to hold at maximum authorized speeds.
There is some margin for entry selection, generally within 5 degrees. So, when an FMS selects a teardrop instead of a parallel it is within the margin.
I've been to more than one meeting in OKC, which were about all this stuff. I don't recall having seen you there.
Controllers don't know squat about holding pattern protected airspace, just as they don't know about CTL airspace, or any other segment of an IAP. However, their airspace managers do and it's them who make sure holding patterns and other IAP airspace doesn't overlap conflicting airspace, etc. Controllers work the traffic and hopefully follow established procedures.