English speakers often do care about the connotation of "propaganda" as something deceptive or manipulative (with the paradigmatic example probably being wartime propaganda which tries to influence populations, supposedly without regard for the truth).
It's true that "propaganda" in the disparaging sense is more applied to political and ideological messages, but you can sometimes see it used about commercial messages when the speaker believes that those messages are especially manipulative, for example when the speaker believes an industry is bad but is wrongfully portraying itself as good by covering up harms that it causes. You might hear this more in connection with an "industry" ("tobacco industry propaganda" or "oil industry propaganda"), but I've occasionally heard it in connection with individual companies. But the negative connotation is pretty strong, so some listeners might be uncomfortable if they don't share the speaker's views of the propaganda author.
One can also say that a book is propaganda in the sense that the book is dishonest and manipulative advocacy, where the author isn't showing respect for the readers.
I wanted to write something about the question of how American rhetoric (and courts) see the relative value, or relative harmfulness, of commercial versus political advertising. But this turned into a complicated discussion that I'm not sure I can do a good job of, so I'm going to hold off on that for now.
> English speakers often do care about the connotation of "propaganda" as something deceptive or manipulative
I know they do. If you read again, you'll notice that my point was not that they don't care about the negative connotations of the word "propaganda". It was that having a separate one for "advertisement" serves as a way to accept the latter as benign.
It's true that "propaganda" in the disparaging sense is more applied to political and ideological messages, but you can sometimes see it used about commercial messages when the speaker believes that those messages are especially manipulative, for example when the speaker believes an industry is bad but is wrongfully portraying itself as good by covering up harms that it causes. You might hear this more in connection with an "industry" ("tobacco industry propaganda" or "oil industry propaganda"), but I've occasionally heard it in connection with individual companies. But the negative connotation is pretty strong, so some listeners might be uncomfortable if they don't share the speaker's views of the propaganda author.
One can also say that a book is propaganda in the sense that the book is dishonest and manipulative advocacy, where the author isn't showing respect for the readers.
I wanted to write something about the question of how American rhetoric (and courts) see the relative value, or relative harmfulness, of commercial versus political advertising. But this turned into a complicated discussion that I'm not sure I can do a good job of, so I'm going to hold off on that for now.