Answer
How much money does an APC waiver actually save?
It depends on the list price, which commonly runs from several hundred to several thousand US dollars per article. The comparison that matters is between publishers: for 35 countries, Wiley grants a full waiver where Taylor & Francis grants 50%. On a charge of USD 2,500 that difference is USD 1,250 for the same paper.
Detail
Where the gap is widest
Ethiopia, Ghana, Kenya, Nepal, Lebanon, Sudan, Tanzania, Zambia and Zimbabwe are among the countries that receive a full waiver from one of the two and half from the other.