In that hypothetical world, I am quite sure that people would adapt to their improved material conditions and still become resentful at wealth inequality. A lesser version of this already exists in the US. Go to a relatively poor US community and it is almost unimaginably wealthy compared to past generations and other places in the world.

The line that people have it so much better than previous generations or other countries is almost always aimed at the lower ranks of society. Nobody tells the billionaires how good they have it.

Inability to save, class immobility, and insecurity of both food and housing are identical problems regardless of whether smartphones have been invented. It's telling who, specifically, advances claims about the notional fabulous wealth of the impoverished in the US.

In any case the assertion that poor communities are in any way better off than their predecessors is only accurate if you push you compare cohorts ~80 years or more apart. After the advent of social safety net programs in the US the working poor were (at least for a time) significantly more able to eventually join the middle class. Modern limitations on earnings and savings that have been applied to these programs has provably reduced this kind of class mobility.

Additionally, the combination of hyperconcentration of wealth, deregulation, and globalized trade have all played a part in the near total elimination of economic opportunity in rural communities.