I know what was said, but it's irresponsible to think it won't happen. If they're not vetted then it allows it to happen, the chance of it occuring is increased because it's an easier route for them to get themselves in to that sort of situation.
I'm not that familiar with the pathology of sexual perverts but I don't think that is how the majority of them operate.
Sure, for some, opportunity will be everything, but for many preparing, grooming and stalking the prey are part of the deal. And there are plenty of opportunities for them do this without them being logged while doing so.
Personally, I'm against all these unlicensed OTT services. Higher yields can be achieved within the current frameworks which include compulsory vetting of drivers and some kind of minimum wage.
But for me, knowing that you were travelling somewhere would useful if I was planning to rob your place. As I say, the tabloids are conditioning to suspect the wrong people of committing the wrong crime. We're encouraged to believe that world is full of violent perverts and terrorists whereas violent crime is in decline and road traffic accidents are the real killers.
For fun we could apply Terry Pratchett's actuarial approach to crime to things like big business' tax avoidance schemes: how many people died in Ireland as a result of underfunded services because Apple, et al. didn't pay the going rate.