A lot of us live in older homes without good insulation. Somewhere in the mid 1900s we simply forgot that "plaster interior wall directly on brick exterior wall" does not provide insulation.

1920s era homes are even worse, single hung windows in wooden frames, no insulation, no conception of managing airflow.

Modern homes are much more efficient, but they're a bit impractical to buy these days, and are increasingly built so shitty that their lifespan is less than their inhabitants.