"Persistently low productivity" sounds a lot like a euphemism for "workers are lazy" but when the owning class want an ever increasing portion of the surplus value of labour, it shouldn't come as a surprise when nobody wants to perform said labour.
In fairness, incomes have been stagnant since the dawn of time. Wages only saw a period of growth because wages were only invented a couple of hundred years ago. Selling time is a product of industrialization. Before that, people only sold things. Now that the vast majority of the population only sells their time, there is nowhere left for wages to go.
During the transition, if 90% of your income is from selling things and 10% selling your time the first year, 50% selling things and 50% selling your time the next year, and 100% selling your time in the third year – there's your wage growth. 900% growth in just three years! How wonderful! Except your income didn't change, so...
Wealth gap gets bigger and bigger, workers feel less and less secure in their jobs and lives, and companies try to blame the people who are making them rich.
Even worse, they inspire infighting between the working and "middle" class. A person making $100K a year is a lot closer to someone making $45K a year than the executives making many millions a year.
A person making $100K a year is a lot closer to someone making $45K a year than the executives making many millions a year.
Not really, because someone making $100k per year has $55k each year to invest in capital. And capital compounds. 20 years later that person will be making millions per year too, while the person making $45k is forever stuck there with no opportunity for escape.
Like you pointed out yourself, it is the wealth gap, not the income gap, that is pertinent.
But in this specific case (the link in OP), the discussion is centred around employee/employer relations. In that context it’s employee compensation that seems more relevant to the discussion.
Employers have control over how much they pay people, so if they are complaining about “lazy people”, it feels fair to point out lowered compensation and benefits year over year if you factor in inflation.