Your 501s are an echo of Steve Job's wardrobe, "black long-sleeved mock turtleneck made by Issey Miyake, Levi's 501 blue jeans, and New Balance 991 sneakers", quoting his Wikipedia entry. Elizabeth Holmes was one follower of that style.
I can assure you that tight jeans came into being many years before cell phones, even if you date from the first demonstration version in 1973.
Fanny packs were in dubious style when I was in college in the early 1990s.
"Today youths ... wear clothes which disconcert their elders, including tight jeans to emphasise a bulging crotch. They spend most of their time strumming on guitars or trendy-looking girls who look as though they’ve just crawled out from underneath a rolling stone. Secretly these girls will worry about tight jeans making a man impotent."
How amazingly influential this mysterious someone was, to influence things some 35 years later!
Certainly more then how the beatnik and hipster styles of the 1950s influenced your generation of HS students.
Since purses are another obvious solution, I place no faith in your interpretation.