Customers who call up Uber through its smartphone application find various levels of rides, from budget commuter cars to premium black sedans. The company says that its low-cost service has proved popular throughout Europe, and that existing taxi associations are fighting to outlaw it because they do not want the competition in an industry whose rules have not changed for decades.

“Consumers are adopting UberPop very quickly,” said Pierre-Dimitri Gore-Coty, Uber’s regional general manager for Western Europe, adding that in cities like Brussels, the low-cost service is the only product that the company offers. “Traditional taxi drivers have always had a lot of power. Every time governments have tried to modernize the industry, it has proved problematic.”

Uber’s other ride-booking services, including those involving traditional taxis and luxury sedans that require chauffeur licenses, charge more than UberPop. Rivals, including Lyft, which is available only in the United States, also offer low-cost ride-booking services, though global regulatory attention has so far focused on Uber.

In India, one of the company’s black sedan drivers was accused of raping a passenger. And in Australia, Uber began raising its rates on Monday just as the police surrounded a cafe in Sydney where an armed man was holding hostages. The move, which Uber calls surge pricing, is governed by an algorithm and kicks in when demand for rides in an area spikes. Many people who were stranded in the area were asked to pay roughly four times the normal rate, according to complaints on social media, though Uber quickly capped how much drivers could charge passengers.

While a Paris judge ruled last week that UberPop could continue operating, Mr. Brandet, the Interior Ministry spokesman, noted that a French criminal court in October had fined the company $124,000 for deceptive marketing, saying that Uber was operating a taxi service, rather than a ride-sharing program. Uber is allowed to continue operating as it appeals that decision.

The October decision “is exactly in line” with the government’s thinking, Mr. Brandet said, which calls for “better regulating the profession to avoid unfair competition.” Those who operate such services, he said, could face two years in prison and fines of up to $370,000.

To adapt to the challenge posed by Uber and similar services, the French government passed the Thévenoud Law. It would require that all drivers who chauffeur paying passengers have a license and appropriate insurance. Drivers for services like UberPop would also have to have 250 hours of professional training, though that is still less than what most taxi drivers, who are considered to be professionals, must have.