“PARIS is the only city in the world where it is hard to find a taxi.” So in 2008 said an embarrassed Nicolas Sarkozy, then France’s president, exasperated by the near-impossibility of hailing a cab on the capital’s streets. He vowed to fix the problem, but backed down after cabbies blocked the streets during days of protest. Six years on, his Socialist successor, François Hollande, is again facing up to taxi drivers, this time as incumbents try to keep out smartphone-enabled private cabs.In rolling strikes this week, scores of licensed taxi drivers jammed the traffic by blocking intermittently the ring-road or périphérique, access to airports and the Place de la Concorde. Their gripe? The emergence of new private cab services, known as voitures de tourisme avec chauffeur, which can be ordered via a mobile app. With 17,600 licensed taxis, the Paris region is not far off London’s total of 22,000 black cabs. But the French capital has a dearth of minicabs: just a few thousand, against 50,000 in London. Until recently, it has been all but impossible in Paris to pre-book reasonably priced, fixed-fare trips.The…