Poverty and violence
Poverty and violence, and specifically how these forces affect a family, can be taken as a central theme. Toby and Tanner are both broken and the signs are everywhere - their ruined home, Toby's failed marriage, and Tanner's years in prison. The viewer can clearly see they are a family broken down by Poverty and violence
Failure
Failure is also a central theme in several ways, Toby has failed as a father and has not seen his children for a year because of fear. Tanner has failed to fit into society, hence the time he spent in jail. Texas Ranger Marcus has also failed and struggles with his pride and insecurity
Corporate America
The notion that corporate institutions in America prey on the most vulnerable in society is the third theme in Hell or High Water This theme is everywhere in the film. It is the reason why they have to go on the bank heist and the reason why a single mother is working as a waitress.
