Bushby has had actual sponsorships, and also sold the rights to a book from a major publisher (all well documented), so you shouldn't read his remark as just bludging off locals for decades.

Rather, any longterm overland traveler, even if they can pay their own way and are even posh, will encounter situations where local people want to extend hospitality and do something to help you, even if they are of much more modest means. Sometimes this isn't actually helping you, because you'd rather sort your own accommodation and food and have downtime to yourself, whereas being a guest requires socializing and energy, but you feel compelled to accept because people want to be seen as kind and generous.