I'd say it's the pace in which modern capitalism operates at, particularly in tech. When the rate of production goes higher and higher due to automation and a global outsource-able workforce, the shareholders chase after higher and higher profits.
Tesla can't outsource globaly and does not have profits yet. Effectivity is about whether burnout brings higher profits, not whether people unable to gain them burnout themselves or those under them due to wishful thinking.
Nothing has changed, and ironically, this whole part of the question - is it better to burn people out and rehire - is a capitalist question, and answered with capitalist goals.
