>> However, inequality has a definite effect on economics and prices, so we can deduce that if the ratio of the two salaries were greater than it already is, while the job remains the exact same, then his mother would be in a worse position

> Inflation is a separate problem

It's not just inflation: supply/demand dynamics will be changed across income levels. For example bidding wars might cause rentals to go up, and the mother will be outbid (see: gentrification or recent news on San Franciso rents)