I think it’s a beautiful thing to pick up a total stranger because you selflessly want to help a fellow Jew. In most cases, the person picking you up, is genuine, and sincere about wanting to help. Sadly, there is a small percentage of people who do not have good intentions. That is one of a few reasons why hitching is taking a major gamble. The other reasons of course would be, that standing in (or near) the street is a danger to the pedestrian from the passing cars (drivers) who may not see them. It is also against the law in many places, the hitchhiker (and the person picking up a hitcher) can get arrested. Most people in the secular world would never pick up a complete stranger. When they see an “orthodox” dressed individual hitchhiking, they think negatively of all Jews, which means the hitcher is inadvertently causing a chillul Hashem.
If people are going to hitchhike anyway, there should be designated safe “hitching” areas. That way when a driver is picking someone up, they wont risk getting rear ended by the driver behind them. It could also be a better alternative, when only Jewish people know of the location, and if C”V, there is a Jewish driver with ill intentions, other hitchers can be there to help, and/or be witness to who the driver is and know the type of car being driven, along with knowing the license plate number. Or perhaps there can be “known” volunteers who do the “pick up” at any given time.