I just want to correct a piece of misinformation in your post. As a travel book reviewer I have reviewed editions of Mr. Hunter's Along I-75 and Along Florida's Expressways many times in the past for various magazines and newspapers.
I contacted Mr. Hunter about your post and he told me that each new edition of his books includes all updates from previous editions plus new editorial material and new suggestions, tips, etc.
When a new edition is published (I believe the current I-75 book is edition 19), Mr.Hunter provides free access to an update website where purchasers who support him by buying the current edition may keep their book up-to-date with major changes such as the Detroit I-75 closure situation. He also provides free downloadable maps and replacement pages.
I have checked his update website and he has a complete section on how best to handle the I-75 southbound closure in Detroit. His "best" detour plan varies according to time-of-day; he has even included a real-time traffic flow map so a traveler can get immediate intelligence about the best route. Incidentally, was it fair of "WC1" to publish this link so anybody can use it?
It is therefore not correct to say that he doesn't offer information for free. He does, but only to those readers who support him by buying and traveling with the current edition. Using an earlier edition is like reading a daily newspaper from last month for today's news.
John Sawden