I remember that there was some sort of public transport very close to the Fallbrook home. They actually passed it in one of the home videos. I don't if it was Amtrak, light rail or bus, but it had a large parking lot that I am assuming was for folks who commuted. Could have come into play?
I think you’re talking about the park and ride at the intersection of Hwy 76 and I15. I think it may feature in the crime, since it’s easy walking from the McStay home, for a vigorous person. There’s no type of public transportation there, as far as I know. Certainly no Amtrak or light rail. But—not that big of a taxi-ride from the Mexican border.