Lacking human connection, Travis develops a stalkery obsession with political campaigner Betsy (Cybil Shepherd) and amazingly manages to convince her to spend time with him. However she's clearly his cultural and intellectual superior and occasionally mocks him. After a terrible faux-pas she rejects him, setting him on a path to violent retribution.
CW: full spectrum 1970s seediness including paedophilia, racism, sexism, homophobia etc.
Another classic I've never previously seen this is actually worthy of the description.
Travis is the archetypal incel inadequate who when spurned turns to violence. When one woman with the agency to deny him rejects him, Travis focuses on one with no agency whatsoever.
His clumsy attempt to 'rescue' child prostitute Iris (Jodie Foster) seems initially well meaning but in the end is not heroic. It's another violent tantrum where through sheer chance the outcome resembles heroism to outside observers. He's not redeemed he's just going with things as they stand.
What do we learn from this? I'm not sure this tour of 1970s misery teaches much but it's still got punch today at over 45 years old and few bits of cinema manage this. 10/10