According to the author what has most contributed to the need for wage earners to organize

Referring to Samuel Gompers, Letter to Judge Peter Grosscup, "Labor in Industrial Society" 1894

The one that contributed the most is The concentration of corporate wealth and power. This situation make corporations able to abuse the power that they have towards their workers by giving them wages that did not even meet average standard of living. The letter is aimed to make workers to unite and stand up against the unfair treatment