Poor mom... I can't imagine the guilt she felt telling him to take a taxi... That was my first thought... And then not knowing for all these years... Heartbreaking... but I also imagine that, being a drug and alcohol user, she'd be a little bored of him doing the same thing repeatedly... Could he have run away without looking back because he felt his mother didn't care about him? Maybe it was the final straw, not picking him up... He could have felt this way for a long time...
whatever it is
Rest in peace