“It’s in the air,” said Peter Dreier, an expert on urban policy at Occidental College in Los Angeles. “It’s infected other people.”

Yet even the triumphs have left some workers cold. The teachers’ strike had been gestating since 2014, when a slate of teachers known as Union Power seized on frustration with ballooning class sizes and lagging pay and swept out the union’s leadership.

The new leaders meticulously prepared to strike with escalating protests and rallies, according to a forthcoming book by the organizer Jane McAlevey. But after the district agreed to many of the strike demands — among them raising wages and adding support personnel like nurses and counselors — many teachers grumbled that union officials gave them only hours to review the proposed contract.

“They wanted you to accept the agreement without any kind of debate,” said David Feldman, a high school history teacher who is part of a fledgling campaign to challenge the current leadership. “That’s kind of a pattern of things.”

Gloria Martinez, one of the union’s vice presidents, said the limited time for discussion was a valid concern. “There were a lot of pressures of wanting to get our students back into the school,” she said. “We should have paused for a bit.”

It is not the only union campaign that has left rank-and-file workers seeking more of a say.

One of the country’s biggest groups of Uber drivers, the Los Angeles-based Rideshare Drivers United, has clashed of late with the two-million-member Service Employees International Union over talks that the S.E.I.U. and other unions have held with Uber and its ride-hailing rival Lyft. The talks explored a way to exempt the companies from having to classify drivers as employees covered by minimum-wage laws and workers’ compensation, which a bill in the State Legislature known as A.B. 5 would require. In exchange, a deal could have made it easier for a union to represent the drivers.