Since the actual definition has only three variables for the TD to consider when determining par, what do you think they're getting wrong?
They're not getting it wrong; they can't possibly be wrong: ", as determined by the Director" is very important.
They are not
interpreting those parts of the definition differently, they are choosing to
not use the definition.
Sometimes, they set aside the definition and set par according to some other rule of thumb, like "reach plus two", or "all par 3s must be ace-able", or "the whole field should expect to birdie", or "the longest hole on the course must have a higher par". That practice is actually getting pretty rare these days.
Sometimes, they are just using the tee sign pars. Tee sign pars are almost always set for the Recreational, Intermediate, or Advanced skill levels - to increase the popularity of the course. In other words, the TDs choose not bother to put more effort into the tournament by setting par for experts. (Which is quite understandable.)
Sometimes, they are holding events on such short courses there would be some par 2s, but they don't call them that because "the pros would kill me". (Again, understandable.)
Sometimes, they decide to pump up par with the intent of creating "lots of eagles!!!" or some similar BS-based hype. (OK, this one actually bothers me. Still, it's their choice to make.)
To sum up, there is fairly widespread agreement about what par
should be, but less widespread discipline in implementing it. Which is probably OK for now. TDs have too much to do already. They need to be free to make the decisions which are right for them.
At some point we will reach a tipping point where it will become easier for TDs to set par according to the definition than to explain why they didn't.
We are getting nearer to (or maybe are already at) that tipping point because of more widespread awareness of the
actual, real, official definition of par; thousands of people watching commentators on videos describe what score pros should really expect on mis-parred holes; and hole-by-hole scores being digitized for so many tournaments.