Oh I figure she was drunk off her ass which is why she called Uber and did not drive which was responsible. For what ever reason the Uber did not drop her off at home but on the side of the road leading to her death. Wanna bet she was puking all over the back of his car and that is why she was thrown out?
Taking the general script Im familiar with and adding what we know, it probably went something like this:
Since we know that this happened at 1 we also know that this isnt a couple "trying to be responsible" or something by getting home to relieve the babysitter something similar as those people leave earlier. Hardcore drinkers tend to stay til just after 2. Nobody voluntarily leaves at 1. She was likely smashed, even if she was a "good" drinker before hand, the last year and half left on the wagon left her out of practice.
She could barely stay conscious and hubby was trying to get her home before he had to carry her. Despite possibly already being sick there, her friends were encouraging her to stay out til close.
By the time their ride arrived the husband was already seen as the bad guy "for ruining her fun". Depending on her state, it didnt take long for her to start puking everywhere or raging and fighting with him (Ubers are generally smaller cars, lunging on the highway in a rainstorm equals ejection at the next exit).
What happened next makes me think it was the latter. If she was puking and barely conscious the driver may have demanded extra fees for cleanup which he apparently didnt and they only gave a 3$ tip. If the driver learned they were broke or ejected them for being sick, depending on how that played out there would have been either nothing paid, $15 and no tip, or $15 and what appeared to be a giant tip (for cleanup).
We know they didnt go far($15), and the driver poured them out. They are relatively young and shes angry that he ruined her fun. "Its not far" in her mind so most likely she decides to walk back to her friends at the bar, or possibly over to where she thinks she remembers an old friend living. Shes likely aggressive and not passed out on someones lawn because if she was the others wouldnt have left her. The other two figure she can find her way home/back to the bar. She may have possibly said she was going to the gas station/restaurant or similar place to get something and she seemed at least lucid enough to leave her there to call another cab or walk once she calmed down.
Both they and she misjudged. The last few shots at the bar are now working their way into her blood stream and she has crossed over the point where shes walking but doesnt really have much in the way of any conscious thought. A dim awareness that the highway goes to where she imagines she wants to be and...splat.
It may seem like a lot of assumptions but even though there are some variations, like which is the more drunk one, how drunk everyone is, where they imagine they want to go, the story still goes basically just like I described but without the splat.