She looks to be of European descent to me, am I missing something?
I agree strongly with you on that. She looks hauntingly like my own mother who also had dark brown hair and eyes.
I think finding out how far off his route the driver was (as stated on Pennsylvania missing) is first priority and would be most helpful in pinpointing where this woman was picked up or heading to. Very curious as to why he would leave his normal and expected route and go to Fayette county PA.
I can't access a map at this moment but Sparrows Point MD to Richmond KY was his route. But he ends up crashing 15 miles South of Uniontown PA, on Route 119 in Springhill township. I think we could be confident that she joined the driver before he diverged from the expected route. And that he probably wouldn't have been willing to take her to a location that would have delayed him by much.
She has house keys but no ID, that suggests she wasn't far from wherever the keys fit and didn't expect to be gone long enough or far enough away to need proof of name/residence. However, I'm of her generation and didn't need or have official id until I was 19 and got a driver's license.
No purse also suggest she has nearby ties. Not taking a purse suggests not wanting to be bothered with it's bulk. Take my keys, my cigarettes and head out the door; be back soon. Earn the $ found or bring it with me. A runaway would bring her purse.
No car keys, so how does she get to where the driver picks her up? Where is he taking her when he crashes? Truck stop and rest area prostitutes wouldn't normally leave those places and truckers have no need to leave their routes to find one. Runaway, hitchhiker, working girl, stow away?
I see prostitute as unlikely (at least with this particular trucker - the large amount of cash could mean she had been working earlier) due to the above paragraph reasons and due to them being off route and in a moving truck. Runaway unlikely due to her age and no purse and having the house keys on her. Could the trucker have been taking her home or to wherever she was going with that cash?
As for her hair dye - to me it looks to be growing out and the darker color closest to her head is natural. If she's listed anywhere it could be with dark blond, red or brown hair description depending on who filed the report.