Amazon Gives Its Workers Another Pay Raise subcontractors for delivery in the US, amid mounting pressure from unions.

Drivers who with Amazon Delivery Partnersor DSPs, earn an average of nearly $22 per hour, up 7% from the previous average of $20.50, the company said Thursday.

The increase in wages is part of a new $2.1 billion investment the Seattle-based online retailer is making in its delivery program. Amazon doesn’t employ its own drivers, instead relying on thousands of third party companies who deliver millions of packages to customers every day.

The company also gave a pay raise to U.S. drivers last year. Last week it also said it would increase wages for frontline workers in the U.K. by 9.8% or more.

According to Amazon, the DSP program has created 390,000 driver jobs since 2018 and the total $12 billion investment since then will help fund safety programs and provide incentives to participating companies.

US labor authorities are increasingly scrutinizing Amazon’s business model, creating a divide between the company and the workers who drive the ubiquitous gray-blue vans.

The Teamsters and other labor groups have argued that Amazon exercises broad control over its subcontractors, including by determining their routes, setting delivery targets and monitoring their performance. They say the company should be classified as a joint employer under the law, which Amazon has fought.

However, labor regulators are increasingly turning against the company.

Last week, a prosecutor for the National Labor Relations Board in Atlanta ruled that Amazon should be held jointly liable for allegedly making threats and other unlawful statements to DSP drivers seeking to unionize in the city. Meanwhile, NLRB prosecutors in Los Angeles last month ruled that Amazon was a joint employer of subcontractors who delivered packages for the company in California.

If no settlement is reached in those cases, the agency can choose to file a complaint against Amazon, which would then be heard within the NLRB’s administrative law system. Amazon would have the opportunity to appeal a judge’s order to the agency’s board and ultimately to a federal court.