[Question] Why has poverty worldwide fallen so little in recent decades outside China?

In this ar­ti­cle, I found this graph of the per­centage of peo­ple earn­ing less than $7.40 a day wor­ld­wide, ex­clud­ing China. That num­ber has barely shifted from 1981 to 2015 - it’s down by 3 per­centage points from 62% to 59%. We can con­trast this with the drop in peo­ple earn­ing less than $1.90 a day: even ex­clud­ing China, this has dropped by 17 per­centage points (from 29% to 12%) in the same time. I played around with the data source for a while, and the $7.40 thresh­old doesn’t seem par­tic­u­larly cher­ryp­icked (nor are the dates). Ex­clud­ing China is not to­tally stan­dard but seems rea­son­able since oth­er­wise the data from this one coun­try would make it difficult to see more gen­eral trends.

The origi­nal ar­ti­cle uses this data (and other ar­gu­ments, like cri­tiques of ne­oliber­al­ism in the 80s and 90s, and crit­i­cism of Rosling’s data sources) to ar­gue that books like Rosling’s Fact­ful­ness and Pinker’s En­light­en­ment Now are mis­lead­ing. To be fair, it makes sense that when you use a higher thresh­old, the per­centage of peo­ple cross­ing that thresh­old in a given time de­creases. But go­ing from 62% to 59% is a very small differ­ence over 34 years! So I’m tempted to con­clude that the de­cline in ex­treme poverty is a less ro­bust in­di­ca­tor of benefi­cial long-term eco­nomic growth than I thought, and that the two books I men­tioned are miss­ing im­por­tant trends in global poverty. Is this rea­son­able?