The van pulled up outside the Altona train station at 7:12 a.m. on Monday with its front seats empty, its steering wheel turning itself, and a small screen on the dashboard that read, in German and English, “Welcome, Dirk.” Dirk Petersen, 44, a logistics manager who had booked the ride on his phone, climbed in, buckled up, and became one of the first people in Germany to pay for a taxi ride with no human aboard but himself.

Hamburg on Monday became the first German city, and the third in Europe after Oslo and Zurich, to authorize a commercial robotaxi service without safety drivers. Forty electric vans operated by a joint venture of a German carmaker and a Berlin software company began carrying passengers across a 55-square-kilometer zone that covers the city center, the port district, and several western neighborhoods. The fleet is expected to grow to 150 vehicles by next summer.

“Germany passed the law in 2021 and then spent five years being nervous about it,” said Katrin Albers, who heads the city’s transport authority. “Eighteen months and 1.4 million kilometers of supervised driving later, the data say the vans are safer than the average Hamburg driver, which, I say as a Hamburg driver, is not the highest bar.”

The vans had 11 minor collisions during testing, all at low speed, and none in which the software was found at fault by the federal motor transport authority, which must approve each operating zone. Fares are set at 1.90 euros per kilometer with a 3-euro base, slightly below the regulated taxi rate, and the vehicles operate between 6 a.m. and midnight in weather up to moderate rain. Snow, Ms. Albers conceded, “is a 2027 problem.”

The city’s 3,200 licensed taxi drivers are not celebrating. “They said the robots would take the night shift first. Now they say midnight,” said Hasan Demir, who has driven a cab in Hamburg for 19 years and represents drivers in a local association. “Next it will be the airport runs, which are the only runs that pay.” The association has asked the city to cap the fleet at 150 vehicles until 2028 and to require that a share of robotaxi revenue fund retraining for drivers.

Mareike Voss, a transport researcher at Hamburg University of Technology, said the more consequential question was not taxis but buses. “Forty vans do not change a city. What changes a city is when this technology becomes cheap enough to run a 12-seat shuttle to a suburb where a bus comes twice an hour,” she said. “That is three to five years away, and the taxi drivers are right that it starts here.”

Mr. Petersen’s ride, 6.8 kilometers to his office near the port, took 19 minutes and cost 15.92 euros. He rated it four stars. “It drove like my mother,” he said. “Very carefully, and it would not go above 48 in a 50.”