Reading this, it's hard for me to imagine a time when Japan would have been, pardon the phrase, a backward country where "automobile and motorcycle engine repairs were done on dirty floors".
When I visited Korea a decade or so ago, I saw a lot of tiny scooter/motorcycle repair shops that might have resembled the description above. (Lots of janky scooters too that appeared to have a lot more miles on them than their manufacturers intended). I imagined that perhaps Korea is where Japan was some decades prior.
While watching the Kurosawa film High and Low (1963) I thought I could sense a little more of the scrappiness of that earlier Japan.
Maybe they weren't. We're getting a claim that is seemingly only attributed to one person, who was recalling something. When did he have this recollection? What was the context? Was he recalling the dirty floors "back then" compared to today's shops? What was his sample population (only a few in poor, rural areas)? Is he (or the author of this) merely styling himself as a "white savior", bringing cleanliness to Japan? Who did he say it to? Let's not forget, Child tasked himself to bring Harleys to Japan when the company wanted him to go to Shanghai. He maybe thought he had to overstate his worth a bit...
Also, I think you are missing some context from bygone days.
In the 1970s, a writer for a magazine like Cycle World would not have thought it shameful to learn from another culture, and therefore wouldn't have realized that describing the history of a non-Western country acquiring intellectual capital comes off as accusatory and racist.
They also would not have identified with Harley Davidson on nationalistic or racial grounds, as the magazine was written by and for people who rode all sorts of other motorcycles and therefore were harmed by protectionist policies.
So I wouldn't take the overall story as accusatory or suggesting Japan "owed" H-D something. In a 21st century context, it definitely would indicate racial animus or chauvinism, but back then, it was normal for people to write from a more detached perspective.
When I visited Korea a decade or so ago, I saw a lot of tiny scooter/motorcycle repair shops that might have resembled the description above. (Lots of janky scooters too that appeared to have a lot more miles on them than their manufacturers intended). I imagined that perhaps Korea is where Japan was some decades prior.
While watching the Kurosawa film High and Low (1963) I thought I could sense a little more of the scrappiness of that earlier Japan.