joe mcD was the MD at DIFTA and he was very thorough in explaining, and requiring that people adhere to the rules, yet all the matches were fun.
he did make local exceptions for hunter seats, and inch or two high, perhaps, or a stool with a back (if the person didn't use the back) and perhaps a few exceptions that i was not aware of.
phil dean (and his faithful sidekicks paolo and jan) maintain pretty much the same situation now. most of the people i've shot with are very aware of the rules that govern their particular class.
i read the rules several times a year and am careful to comply. in my limited exposure to other clubs, and people who visit DIFTA from other clubs, i can't really say i've seen anyone who disregards the rules.