There were two other issues that I raised in class about the use of life expectancy as a measure of well-being. The links aren’t required, but the gist of them is.
Some information about how premature infants are counted can be found in this piece from the Centers for Disease Control. Most of this is about how infant mortality is measured across countries, and in some countries a prematurely born baby is not counted as a person unless it is big enough or survives long enough. This will clearly influence life expectancy statistics if some countries (like the U.S.) essentially count a lot of lifetimes of zero years.
Some information about how homicide rates have been higher in the U.S. for centuries, which will lead to lower life expectancy, can be found here.