Exactly!
Why would anyone want to pay for something that is easily available for free!?
Does not make sense.
Consider that I am a new DM. I have heard from a more experienced DM that ToA "has everything someone needs to run adventures in Chult". I have heard this from multiple experienced DMs. I discover this simply is not true. I find ToA is lacking information. I am forced to Google because of this falsehood.
Ubtao is mentioned in the text where who the locals worship is relevant. The book is lacking in the index department though.
More relevantly no portfolio is mentioned. His domains are not mentioned. A mention is not the same as having relevant information that can be used. We can infer Chult is connected. But in what way. As protector only? As creator? We can infer that dinosaurs are connected. We can infer later in the book that mazes are somehow relevant. Crucially there is no central relevant point in the book that offers this information.
None of this information is in the much vaunted 2nd or 3rd edition FR sourcebooks either.
Page 23 of FRM1 Jungles of Chult
"Ubtao-Worship
Many Tabaxi venerate Ubtao. These people believe that Ubtao created the jungle and all the humans and animals that populate this hot, green world. Ubtao also raised the holy city of Mezro from the jungle with his own hands and resided there for a time-until the people drove him into the heavens with their nagging demands.
"The Maze of Life
It is believed among these Tabaxi that Ubtao created the jungle as a sort of test for his people, a maze for them to pass through on their way to a heavenly afterlife. They also believe that each life can be represented as a maze.
"The Children of Ubtao
In Chult, dinosaurs are often referred to as the Children of Ubtao. The monstrous lizards, unlike humans, demanded nothing of the creator god once they were placed in the jungle, so some of the faithful consider them the favored creation of Ubtao."
This information is telling us Ubtao is god of Chult. He is god of Mezro. He is god of the maze of life. He is god of dinosaurs.
The text goes further in offering mechanics to play a priest of Ubtao.
The 3e FRCS has similar information to the portfolio of Ubtao in less words. His connection to Chult is even more concrete. This is on page 103 and page 104 of the Chult section. Page 234 gives you the alignment of Ubtao. It gives you his domains. It gives you his favored weapon.
But I guess
none of this information is in both the 2nd or 3rd edition FR sourcebooks.
Do you expect an FR sourcebook to tell you the name of the chieftain's second wife for the unnamed village 16 miles south east of Port Nyanzaru?
I do expect that ToA gives at least brief descriptions of the locations it gives on the map. It is an adventure. Yes?
The 3rd edition book has one page on Chult, and one short paragraph on Port Nyanzaru. ToA has a whole chapter on Port Nyanzaru alone.
FRM1 Jungles of Chult is an entire mini-setting devoted to Chult. ToA offers less than this.
And if they don't know that a place not on the map is part of another country their head will explode?
No. They will be scratching their heads why they cannot use this.
I say again, what you are after is fictional-history-porn, not something that is actually useful for playing D&D.
I am asking about things that are actually useful for running adventures in Chult. Explicitly for running adventures in Chult. None of what I am asking for is fictional-history porn. But then again you did say none of the information on Ubtao is in the much vaunted 2nd or 3rd edition FR sourcebooks. So.