...In London, it is helping black cabs to fight back against the minicab operators such as Addison Lee, which have booking apps of their own. If passengers can use an app to hail a black cab, goes the Hailo thinking, many will do so in preference to booking a minicab, because the black-cab driver—who must pass onerous exams—knows London better and has all the historical, visitor-friendly associations of a trade body first licensed in the 17th century.