I think that Yeltsin had his own experience of shopping (or otherwise getting stuff shipped) from a "special distribution center" which he knew was unavailable to 99.8% of population yet had way worse selection of goods than the random USA supermarket. It was whatever stuff they could buy in Finland, basically.

He had a family. Personal experiences are hard to beat. He also started his career in Yekaterinburg, from some mid-range position, so he was not that detached from the life of common folk. He just saw a very different kind of life which does not translate to knowing things in theory.