I hitch & pick up some hitchhikers (except the ones who haven't showered in years), but it seems a simple matter of fact that hitchhiking makes you more vulnerable on both sides of the deal. I don't think it's wrong to consider the risks.
Also if we are to compare statistics, the article puts forward 0.04 murders per day related to hitchhiking in California. Ok, well there's 7.7 traffic fatalities per day in California. But how many people drive on the road each day, vs. how many people hitchhike?
If there were 1 million cars on the road in California each day, there would have to be 5,200 hitchhikers each day for "risk parity" for the two activities. That is, choosing to drive your car or choosing to hitchhike would be equally risky. If there are less hitchhikers per day than that, it is more dangerous than driving- if there are more, it is less dangerous than driving.
The point being that while hitchhiking is not the nation's biggest source of violence, the risk is not as small as the article tries to paint.