And forever the Ubers circle—the uncomfortable truth of empty trips.

Whoever drives through Berlin, Frankfurt or Munich on a weekday will notice a phenomenon that has, in recent years, developed almost unnoticed into a fixed part of the cityscape. Between delivery vans, bicycles and taxis, countless black or gray Toyota Corollas roll through the streets. Many carry no advertising, no taxi sign, and no recognizable branding. But those who look more closely quickly recognize: These are rental cars that are mediated through platforms such as Uber or Bolt.

The vehicles are everywhere. And they are astonishingly often empty. That raises a question that is astonishingly rarely asked in political debate: What actually happens between two trips? For years, the platform companies have maintained a narrative that was as catchy as it was politically effective. Rental cars, so the argument goes, would efficiently bundle traffic flows, reduce empty trips, and thus contribute to a more sustainable mobility. Fewer private cars, better utilization, more efficiency. That was the promise.

The reality on German roads, however, tells a different story.

The return obligation exists – on paper

The German Passenger Transport Act deliberately distinguishes between taxi traffic and rental-car traffic. Taxis are subject to tariff obligations, obligation to transport passengers, and operating obligations. In return they may pick up passengers directly on the street and stand at taxi ranks. Rental cars receive different freedoms. There is a central restriction: after completing a job they must generally return to their base of operations, unless a new assignment already exists.

This so-called return obligation is one of the cornerstones of regulation. It is intended to prevent rental cars from effectively operating like taxis without having to take on their duties.

In theory the rule is clear. In practice, it seems to be almost non-existent in many places.

The city as a waiting zone

Whoever observes the surroundings of major train stations, airports or heavily frequented hotel locations quickly recognizes a pattern. Rental cars often do not return to their operating bases. Instead they position themselves at strategically advantageous locations and wait for the next assignment. Officially they are not there. In fact they are nevertheless present.

Sometimes they make slow laps around the block. Sometimes they switch parking lots every few minutes. Sometimes they roll seemingly aimlessly through the neighborhood. The digital platform replaces the traditional taxi stand.

The smartphone becomes the stopping point. The next assignment is often only a few minutes away.

For the platform economy, this behavior makes sense. The closer a vehicle is to potential customers, the shorter the waiting times. Utilization increases. The matchmaking platform earns more money.

However, for transport policy a problem arises. For each of these search-and-wait processes, traffic is produced.

The uncomfortable truth of empty trips

Particularly noteworthy is the discrepancy between political communication and observable reality. The discussion about the obligation to return to the base has in recent years regularly been framed with environmental arguments. Critics of the rule claimed that the mandatory return to the operating base would cause unnecessary miles and increase emissions.

This argument sounds plausible at first. However, it assumes that rental cars would actually comply with the return-to-base requirement. For years there have been substantial doubts about that.

Numerous court proceedings, official inspections and investigations have repeatedly yielded indications of systematic violations. Municipalities regularly report difficulties in monitoring. Even where digital control instruments have been introduced, enforcement remains laborious. The result is a state that many taxi operators have lamented for years: On paper there is a clear regulatory framework. In practice, it is often observed only to a limited extent.

The Competition of Inequalities

For the taxi sector, it's not only about legal niceties. Can a market function sustainably if participants are subject to different rules? A taxi is not allowed to freely set its price. It must accept transport assignments. It must be available around the clock, even if a ride is hardly profitable economically. It must operate in accordance with fixed tariffs.

Platform-mediated rental cars, on the other hand, can flexibly deploy, avoid unprofitable areas, and concentrate their capacities on particularly profitable times and locations.

An additional effect. While taxis without passengers often wait at designated stands, many rental cars move continuously through the street space. For pedestrians, this creates the impression of high availability. In fact, they are often vehicles looking for the next assignment. The city becomes a mobile waiting loop.

The political dilemma

The Federal Court of Justice has only recently reaffirmed the fundamental legality of the return obligation. Legally its significance remains undisputed. Politically, the situation remains complicated.

Federal and state governments have the legal instruments. The enforcement, however, largely lies with local licensing and supervisory authorities. Many of them operate with limited personnel resources. At the same time, the number of vehicles in the metropolitan areas continues to grow. The platform companies argue that they are merely intermediaries. Responsibility lies with the connected rental car companies.

The municipalities, in turn, point to a lack of enforcement options. And the established transport companies observe how a market develops where rules do exist, but their enforcement lags far behind.