On balance Uber/mytaxi/et al is probably safer than just jumping in with any stranger displaying a "taxi" sign - particularly in Ireland where thousands of convicted criminals are licensed, not to mention millions of immigrants with unverifiable backgrounds - according to the drivers' own representative bodies.
Of course, there is no foolproof system but the internet tracking acts as a deterrent given that offenders are far more likely to be caught if they operate with an app based rideshare firm. In Ireland all Uber and mytaxi drivers are licensed by An Garda Síochána and, similarly, in Malaga and London all are licensed by the relevant authorities. Interestingly, Uber's Malaga base seems to employ a lot more lady drivers than in other cities, probably not far off a 60-40 gender balance.