Well well well. Amazon's selling policies may be getting quite interesting. It appears that they have "notified publishers who print books on demand that they will have to use its on-demand printing facilities if they want their books directly sold on Amazon's Web site". That's a direct quote from The Wall Street Journal and several other credible news sources.
This reminds me of the video rental industry. Blockbuster's exclusive deal with the Weinstein company shut out, or tried to, independent video store retailers from renting Weinstein DVD's. It didn't work but monopolies do exist in business.
Looks like Amazon's throwing their muscle and threatening POD (print on demand) publishers. Some observers feel Amazon is targeting subsidy publishers. It could be as that's a very lucrative business. (Personally, I feel subsidy press is a big rip-off for most publishers but I guess it has its place in the publishing world.)Anyway, I'm getting off topic.
It is true that BookSurge does not offer distribution through any channel other
than Amazon.com. That's pretty limiting. It looks like Amazon's new business model is simple: Print your POD books with Booksurge if you want them to be sold by Amazon on Amazon.com. If you have another POD source, Amazon will not sell your book.
It'll be interesting to see if this works for Amazon. I bet not but time will tell.