That first graph in particular makes me very suspicious. Though the article claims that it has accounted for those not engaged in market-economies (i.e. those who still live via subsistence farming either outside or partially outside the market economy, e.g. a large [but diminishing] part of the Papuan population), that actually isn’t possible to factor into a $PPP using neo-classical economic theory (i.e marginal utility theory), since to ‘derive’ exchange value for things not bought and sold at market is impossible by their own logic because non-market exchange appears identical to non-activity. Other indicators like the 'World Bank Development Index' I know are skewed for countries like Papua New Guinea because of the large amount of people more or less outside the cash economy. So it seems to me to think that there is some very fishy manipulation of the numbers going on.
Also, 1.90$ PPP is an absolute pittance, and the poor souls who have to live on that little are in dire straits indeed, but placing people who have 1.91$ PPP a day in the same category as people on 100$ PPP or 10000$ PPP a day is ludicrous. In fact, if one sets the threshold higher (at around 3$ PPP a day) the graph would look very different; if I remember rightly from an essay I wrote a few years ago for university where I looked at lots of world bank graphs, in 2011ish there were somewhere around 3.5 billion people living on 3$ PPP a day. (Interestingly, assuming a relatively stable trajectory in the intervening years between 1970 and now, the ratio of green to red would actually remain more or less the same as it had previously if the cut-off were 3$ PPP a day).
Though in my experience neoliberal economist produced statistics are usually very selectively chosen when one looks into them further, it might be true that there has been a reduction in extreme poverty (i.e. 1.90$ PPP a day). This would clearly be a good thing (though not any kind of actual solution to poverty, since poverty is structural, not aberrant); though if it were true it would be interesting to look at where that might have occurred and why – stuff that isn’t provided, they just blather on about how great ‘trickle down’ economics is without providing evidence or argument. They have likely picked 1.90$ as the line because they found that it fit their narrative the best.
Additionally, starting in 1810 (which is fifty years after the enclosure acts that destroyed the commons in England) is intellectually dishonest, since the onset of the industrial revolution brought with it a brutal spike in poverty, reduction of life expectancy, diminishing of the control women had over their own lives,* etc. If we went further back to before the start of capitalism, and assuming subsistence or semi-subsistence economies were placed in the green, then the onset of capitalism and the ramping up of colonialism that accompanied it would look like a sharp red spike as people were forced from the countryside to the metropolis, and as colonialism increased with a vengeance in order to supply the new mills (i.e. the ‘Scramble for Africa’, ‘indirect’ domination of China, etc.). Though that wouldn’t fit well with the trajectory-narrative they are spinning.
There is a large contradiction going on the minds of people who write articles like this: that while they would never publicly defend slavery, their arguments as to why capitalism is somehow OK are identical to the arguments that were trotted out by apologists for slavery: that it actually improves the lives of those forced to work under it, that things are getting better, that all that needs to be done is to refine the basic system, that if it didn’t exist the economy would be upset, etc.
The wage relation remains one of domination and alienation regardless of how comfortable or uncomfortable the conditions of it might be. Domination should be opposed because it is crippling to human self-realisation; ‘kind’ masters are still dominating their slaves; capitalism with some provisions for welfare is still exploitative.
*There is a book by Silvia Frederici called 'Caliban the Witch' which, among other things, talks about how the enclosure of the commons at the beginning of the industrial revolution was disastrous for women, it is well worth a read.