As an example, allow me to clarify some matters that might not be apparent to someone approaching English as a second language.
Firstly, child labor regulations and food inspection are not the titles of laws, they are classes of laws; this is why they are in lowercase instead of capitalized like the USA PATRIOT Act. So you see, it was not defending the application of laws by their title but instead by their category, an easy mistake to make and you shouldn't be embarrassed about it but I thought it should really be corrected. After all it is nice to be able to understand the difference, as subtle as it is.
Also as you will note I slightly corrected the actual title of the USA PATRIOT Act because, while also a minor quibble there are all sorts of jerks out there who will take up any arguable point and make it cause for battle! Especially when combined with the "who actually read the" bit right before.
Another thing that has probably escaped you, not having a first hand familiarity with American culture is the little nuances of the blurb talking about child labor regulations etc. Perhaps it is unintentional but there are political forces in the U.S that would like to get rid of these and other classes of laws that exist to restrict some things that businesses might otherwise like to do, like having children work in factories and selling food that has been made in unsanitary conditions, and so when I see marketing for something that seems to argue against these classes of law I worry that the book being marketed actually argues against them - I suppose you can see why that might be, right?
Anyway, as I haven't read the book, which you pointed out, I can't really say if it is like I suppose when I read the marketing for it, but as I said the marketing "makes me think" it is, if it shouldn't make me think that then the marketing is bad marketing but if it should make me think that it means that the book hopes to get people who are predisposed to side with those political forces to buy the book. Perhaps the book might even be so written as to even more convince people that these classes of regulation are a bad thing and for this reason I suggested anyone reading the book should read another book called the Jungle which was an initial cause in getting at least the food inspection class of laws passed.
So the upshot of that bit of nuance was I was not actually judging the book by it's cover, which seemed pleasant enough, but by it's marketing which perhaps only incidentally implies the book is harmful in some way. Of course I was only being facetious when I suggested anyone read The Jungle because I don't think it was actually that good but I just meant that the people who subscribe to the theories that those classes of law are bad things seem to labor under some sort of ahistoricity and as that is a lack of knowledge it would be nice if the lack could be rectified somehow.
Finally when you say "there is always a gallery of opinionated people who will gladly judge a book by its cover with no less certainty, and with even more smug self-importance, than they would by its content." oh boy, don't I know it! It really does seem some days that even the most passing and light-hearted of comments will bring some pretentious little martinet out of the woodwork, taking personal affront, and wanting to start a battle over it all.
This is really why I wrote this overly long reply to correct some of what you wrote, as admirable as it otherwise might have been, because I would hope to keep you from being drawn into a confrontation with one of these combative types, who, as I noted before, seem intent on getting the smallest mistake or deliberate misreading as a tool to spitefully attack your character.
on edit: minor grammatical fixes.