Which is safer — Uber or a taxi? There's no clear answer

The taxi industry, facing an existential threat from Uber, has highlighted a series of incidents as evidence that an Uber trip is a gamble passengers should not take.

Nor does San Francisco's district attorney, though his office is spearheading a lawsuit that alleges Uber misled passengers into believing its driver background checks are the most comprehensive available.

Many law enforcement experts say a fingerprint search is the most comprehensive way to check someone's background, and taxi regulators typically require one.

Uber counters that fingerprint checks are imperfect and that its background check process — which it says includes searches of motor vehicle department files and several criminal databases going back seven years — is excellent.

In their lawsuit, San Francisco prosecutors detailed how police there and in Los Angeles found 25 Uber drivers who had serious criminal histories that were not flagged during the background check or may have been disregarded by Uber.

Uber says that in 2014, at least 600 active taxi drivers who also applied to Uber in San Diego, Los Angeles and San Francisco failed its background check for problems such as violent crimes.

The national Taxicab, Limousine & Paratransit Association has a website listing news reports of assaults, rapes and other violence against passengers or pedestrians by Uber or Lyft drivers as part of a campaign it calls "Who's Driving You?"

According to a document compiled by the city, in 2015 Uber drivers allegedly were involved in 13 sexual assaults and one rape; taxi drivers, five; and Lyft drivers, six.