In their 2018 contract negotiations, UPS and the Teamsters agreed to create a new job type, with lower pay, to service demand for weekend e-commerce deliveries, a trade-off that some union members resisted.
In their petition, the unions ask the F.T.C. to study whether Amazon forces its third-party merchants to buy its delivery fulfillment services if they want to rank high and succeed on the site, a move that they say could harm competing shipping and logistics providers.
Amazon said its fulfillment services were optional, but many sellers loved them “because it gives them peace of mind knowing that shipping logistics and customer service are taken care of 24-7, year-round,” a spokesman, Jack Evans, said in a statement.
A spokeswoman for the F.T.C., Betsy Lordan, said the agency had received the labor groups’ petition.
In 2000, the Communications Workers of America tried to organize Amazon’s customer service workers, as an outgrowth of its work with the telecom industry. The company pushed back, and the unionization effort failed.
The union has since followed how the company affects its industries. It represents workers in AT&T’s retail stores, which compete with Amazon for phone sales, for example, and the union in January announced plans to organize tech workers, starting with people in the gaming industry.
Tom Smith, head organizer at the communication workers’ union, said it turned to the F.T.C. because much about Amazon’s business is still a mystery, even to a union that has followed it for two decades. “We see a company that we know very little about, that is very secretive, that there are just tons of unknowns,” Mr. Smith said.