Do Ameritrash Games Tend to Go Out of Print?

My childhood best friend has been in town in recent months due to a lengthy work project, so we have been playing board games together lately. Even though our lives took very different paths after high school, our shared background made us both fans of Ameritrash games. Since he travels frequently for work, he is particularly interested in Ameritrash games that can be played solitaire, especially if they are portable enough for travel. These same games are nearly always suitable for co-op play, so it's easy to showcase these games by playing them with him.

Unfortunately, many of my favorite games are out of print, so he will need to pay a premium to get a copy. Some were Kickstarters, like Camp Grizzly, The Vesuvius Incident, Saltlands, and Masters of the Night, and never got reprinted because that seems to only happen with the really big and popular kickstarters. Other games were published by major publishers but went out of print anyway, like Arkham Horror (2nd), Space Hulk: Death Angel, Escape from 100 Million B.C., and Warhammer Quest: Silver Tower.

Is this just a common phenomenon and I only notice it happening to my favorite games? Or is this the inevitable result of the euro bias at the highly influential BGG site?

There's many different facets here. First, the older the game the more likely it is to be unavailable. Everything you're listing there is relatively old.

The second is Ameritrash centric, in that IPs are not retained in perpetuity. Anything with a license is unlikely to remain in print multiple decades. It's all on borrowed time.

There are many Euro games out of print, however. Great ones. Tigris & Euphrates is currently unavailable.

Yes, it's not genre-specific and many of the titles you mention have a variety of reasons behind their absence. Arkham 2nd has been replaced by other titles and a new version. Space Hulk: Death Angel was a license that FFG lost when they started producing their own minis games. Silver Tower is subject to the vagaries of GW who are always chasing the latest shiny thing.

As Charlie points out, there are many classic Euros (among them several other Knizias, like Samurai and Taj Mahal) out of print. Most of the time it's just an economic decision and shelf space (warehouse and retail) is limited. I doubt that BGG has any significant influence, since most of the money these days is in ginormous Kickstarters, which are usually far more toward the Ameritrash end of the spectrum than the Euro end (noting again that both of those definitions hold little real meaning these days.)