For decades, the attitude of unions and their advocates to increased automation could be summed up in one word: no. They feared that every time a machine was slipped into the workflow, a laborer lost a job.

The Covid-19 pandemic has forced a small but significant shift in that calculation. Because human contact spreads the disease, some machines are now viewed not exclusively as the workers’ enemy but also as their protector. That has accelerated the use of robots this year in a way no one expects to stop, even after the virus is conquered.

“If you keep me six feet away from the other worker and you have a robot in between, it’s now safe,” said Richard Freeman, a professor of economics at Harvard University, who studies labor. “And the robot companies are selling that as a solution and the unions aren’t going to say, ‘No, you should have the workers standing next to each other so they get sick.’”

The result is the spread of windshield-mounted toll detectors, automated floor cleaners at factories, salad-chopping machines in grocery stores, mechanical butlers at hotels and electronic receipts for road pavers. What remains less clear is where the men and women who used to do some of those jobs will work.

The impact of technology on employment has been a topic of anxiety and study for generations with mixed results. Cars didn’t kill trains, television didn’t end radio. When banks installed ATMs, they hired more people, not fewer, because the variety of their services grew. But machines have eliminated many jobs, and the current wave will prove to be no exception, especially with public health a top concern.

“When we come out of this crisis and labor is cheap again, firms will not necessarily roll back these inventions,” David Autor, an economist at the Massachusetts Institute of Technology, said at a September webinar of the Federal Reserve Bank of Philadelphia. “These are kind of one-way transitions.”

That’s what worries union leaders.