Why are Amazon and Starbucks workers striking over the holidays?

Thousands of Starbucks baristas and Amazon employees are currently on strike just days before Christmas, protesting their respective retail giants nationwide during the busiest shopping season of the year, according to their unions.

International Brotherhood of Teamsters President Sean O'Brien, whose union is representing the Amazon workers, drew attention to the timing in his statement released upon the strike's launch.

"If your package is delayed during the holidays, you can blame Amazon's insatiable greed," O'Brien said in the Thursday statement.

The unions chose to strike over the holidays for two overlapping reasons, experts told ABC News: Workers retain maximum leverage if they can disrupt a company at a moment of roaring sales; and the public is more likely to pay attention at a time when Amazon and Starbucks tend to be on customers' minds.

"This is a time when both companies make a lot of money," Kate Bronfenbrenner, a labor relations professor at Cornell University, told ABC News. "The unions are being strategic about when to strike."

Nearly 9,000 Amazon workers on Thursday began what they are calling "the largest strike against Amazon in U.S. history," targeting facilities in New York City, Atlanta, Southern California, San Francisco and Illinois.

The Teamsters say they have organized 20 bargaining units at various Amazon facilities, calling on the company to formally recognize unions at each location and begin negotiating workplace conditions.

In response to ABC News' request for comment, Amazon spokesperson Eileen Hards said the striking workers are not Amazon employees.

"For more than a year now, the Teamsters have continued to intentionally mislead the public – claiming that they represent 'thousands of Amazon employees and drivers'. They don't, and this is another attempt to push a false narrative," Hards said. "What you're seeing at these sites are almost entirely outsiders – not Amazon employees or partners – and the suggestion otherwise is just another lie from the Teamsters.

On Thursday, Starbucks Workers United, a union representing 525 Starbucks stores in the U.S., said that baristas in Los Angeles, Chicago and Seattle would go on strike in the coming days.

Five days of escalating strikes began Friday and will continue until Dec. 24 in "three of the company's priority markets" during what it called the company's busiest days of the year, Starbucks Workers United said.

In February 2024, Starbucks Workers United and Starbucks announced they would work on a "foundational framework" to reach a collective bargaining agreement for stores, something the union says has not come to fruition.

In response to ABC News’ request for comment, Starbucks spokesperson Phil Gee said the company has not experienced a significant impact from the strike.

“We are aware of disruption at a small handful of stores, but the overwhelming majority of our US stores remain open and serving customers as normal,” Gee said.

In a previous statement to ABC News, Starbucks said it remains willing to continue negotiations with the union. "Workers United delegates prematurely ended our bargaining session this week. It is disappointing they didn't return to the table given the progress we've made to date," the company said. "We are ready to continue negotiations to reach agreements."

Paul Clark, professor of labor and employment relations at Pennsylvania State University, said the strikes aim to derail company operations when business is humming.

Both the Teamsters and Starbucks Workers United have sought to disrupt the companies by targeting locations in major cities, where even a hiccup in service could impact a large number of customers, Clark said. Each union represents a relatively small share of the respective company's workforce, however, making it unlikely that the workers will impose a significant disruption, he added.

The Amazon workers said to be striking represent less than 1% of the company's 800,000 operations employees. Starbucks counts thousands of U.S. stores, meaning the union represents a fraction of its locations.

"The likelihood that this will have significant economic impact on those companies is probably very small because of the small subset of employees involved," Clark said. "The bigger benefit of the strikes for the unions is the increased attention that it draws."

Diego Franco, a barista at a Starbucks in the Chicago suburbs, told ABC News that workers began picketing the store at which he works at 4:30 a.m. local time on Friday.

"Our regulars showed up at the same time of day as usual, and we caught them at the store, saying we're currently on strike. Most of them walked back to their car and went elsewhere," Franco said.

Workers at the store filed federal charges against Starbucks over alleged illegal retaliation against union members, Franco said. Striking workers are also pressuring Starbucks to provide a reasonable offer in contract negotiations, he added.

When asked whether the holiday timing of the strike could elicit backlash from customers eager for their coffee, Franco said, "They should be frustrated with the company. We're the ones who serve them. We're the faces they see every morning."