It's true in the USA in the sense of the article A Glimpse of Your Expenses from 100 Years Ago:
Take-home pay in 2015 vs. 1915. Census Bureau data show that the median household income, measured from 2009 to 2013 (the most recent data available), is $53,046. Back in 1915, two years after income tax came on the scene, you were doing about average if you were making $687 a year, according to the Census.
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Today, that $687 would be comparable to earning $16,063 a year, according to an inflation calculator on the Bureau of Labor Statistics' website. So Americans' buying power has improved considerably in the last century.
See also the US Bureau of Labor Statistics article The life of American workers in 1915
Douglas (1930; reproduced in US Bureau of the Census 1949) reports average annual earnings across all sectors in 1915 at $633. Inflating this to 2015 dollars using the US Bureau of Labor Statistics historical Consumer Price Index calculator yields a current dollar equivalent of $14,711. The BLS employment report from April 2015 reports mean weekly private nonfarm earnings of $858. Thus, it would take 17 weeks of work at the average US weekly wage to earn a full-time annual 1915 income