Most of the zombies you find walking around now, years after the day, are leathery skin and bones, walking gristle. It’s the exposure: standing in the rain and snow and wind for a decade, bug-eaten and sun-dried.
You only find fresh ones in the buildings. We keep finding good as new zombies in bathrooms while searching for medicines. The number of people who died while kneeling on the bathroom floor, retching, face against the porcelain, must have been astronomical. They must go dormant after a while with no food; but as soon as we open the door, up they stand.