I long ago stopped picking up female hitchhikers for just this reason. (And, more recently, I've stopped picking up any hitchhikers, for mostly the same reason.) If there's someone broken down at the side of the road, these days rather than stop I'll just call 9-1-1 and report a motorist needs assistance. Between the chances of being carjacked and the chances of being accused of sexual (or other) assault, it's just not a good idea to be a good Samaritan these days. (Sadly)