The point UM is making in its defense isn't really that "everyone does it". The point is that "everyone does it (differently) because no one really knows how to properly interpret the rule." Clearly, if UM found that - contrary to hiding their rule violation - other schools were actually advertising said infraction, then neither the letter nor spirit of the law is understood by anyone. That a few schools may not be in violation is either a function of a) pure accident, or b) legal counsel's opinion that results in an absolute policy restriction that may actually exceed what the NCAA intended.
Which then boils down to intent. There was no intent to violate the NCAA rules, as UM and Rodriguez point out in their reports. It was purely a function of not knowing the correct interpretation. Considering the labrynthine nature of the NCAA rule book, (and this rule regarding "countable" hours, who is a "coach" for this purpose, in particular) this was inevitable.