buffalobill wrote:
is it possible they are not common to your climate due to condensation,
freezing, or ocean salt air corrosion?

Nope. Washington DC isn't known for excessive amounts of those things.

The more likely explanation is that the market for good gliders is
small. My neighborhood is full of 50's houses that were built with
all-metal aluminum gliders. Most of them have been replaced, and I
don't know of a single example of a house that didn't use solid vinyl
replacement windows. Among houses that use windows based on wood, the
dominant choice around here is double hung. So companies that blow off
the wood glider market are following a certain economic logic.