>>149449935 (OP)
Positive role models Mother-Son duos are just exceptionally rare outside of straight up "Jesus and the Virgin Mary". Mentorship roles that aren't familial are even rarer.
If an older lady younger boy duo is present, it's usually either part of a full familial ensemble, a "big sister" or "precocious crush" dynamic, or "mommy issues" horror like Marion and Jason Vorhees in Friday 13th.
As for why, it's really hard to say beyond brushing it off with too vague a term like "the Patriarchy."
For one, female mentors like a mother are too often either background, or a sacrifice in the background (think of all the dead Disney parents). For another, Patriarchal expectations of male independence and becoming a provider or hero is incompatible with keeping a strong mentor relationship with an older female character and staying under her wings. It's generally presumed a father figure teaches things a boy ought to know in order to become a classic hero. It's generally presumed a "momma's boy" is weak.
Women in the classic hero's journey usually are set to be the role of "the temptress/siren," the "goddess" or simply a "reward."
A coming of age story is generally also breaking apart from a maternal figure.
Disagreement with a mother/aunt/older woman is just generally more interesting, like with Archer or whatever. There's that stereotype of "overprotectiveness" that one has to break off from too.
Also, I posit that a generally smaller taboo for an older woman getting it on with a young man means conversely that people might presume such a relationship might inherently become romantic in a way that same gendered mentorship duos don't. Boys are considered horny by default.
An older woman and young boy/man duo just doesn't have that much commercial appeal. It doesn't fit into a power fantasy—they'd be made fun of for being a Momma's boy, not independent, emotionally complex.
