Page 143: It's still 1sp per day.
I know what the hireling page says, but that is not a specific mention and more of a general for players hiring unskilled people, which given the professions mentioned seems to be more of an average.
That said, the rest of your post makes sense and explains the costs on page 159.
Most Africans live on under $5 per day.No one today can manage a modest living using a pure barter economy, and yet according to the Player's Handbook they manage it for the typical DnD world.
It creates a problem that a simple banquet costs $1,000 per person under that economy. I can think of no banquet I have ever been to that cost that much per plate.
Also, you are forgetting that most tend to live on 1 silver a day, or about $10 under your calculation (Source: Player's Handbook, page 143). Using the figures provided by Celebrim on the previous page, that means the typical person lives on only $3,100 a year.
Thanks for the reply, but I didn't mean what actual copper is worth in the real world in U.S. dollars. I meant, what the buying power of a copper piece in D&D 5th edition would translate to in real U.S. dollars.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.