Sometimes the signs can be intimidating as ****, with the overall message of: "Gaper, keep your skis and ass the hell out of this wild untamed terrain." (I saw such signs pretty much "blocking" access to that chair below the vasquez cirque at WP which clearly is for expert skiers who are in groups... b/c if a single got lost or injured there they'd be toast)
Other times I've seen "Warnings."
There ARE ropes and some kind of "entrance gate" to the Vasquez Ridge bootpack. I didn't go over to actually read the sign, since the windchill was -19 and I really wanted to get away (but the sign was a good page worth of single-spaced text). It looked pretty serious to me.
Now, some places have general intimidating warnings (such as Jackson's famous warning statement in tram dock, but that's different; it's not like it's a specific warning tied to a rope in the middle of the mountain).
I've only been two places out west (WP and Jackson). At Jackson, overall I feel the marking is pretty good... you'd be hard-pressed to unknowingly ski off one of the gigantic cliffs, out-of-bounds, or into terrain you would not be qualified for. Maybe everyone doesn't feel the same way there (I have been obsessed with Jackson for like 12 years and have done EXTENSIVE web-browsing, looking at my own photos, etc, so I would know where boundaries are where maybe someone new to the area wouldn't).
Even in the east there is this "grey area." Take "The Slides" at Whiteface... is it backcountry, or inbounds? It must be one or the other, yet there is the "stipulation" you must have avi gear and two other people to go ski it. Also, at Stowe (it's been about 13 years since I was there), I seem to remember they ENCOURAGE people to take the "45 minute hike" up to mansfield, which is straight-up vermont wilderness, but don't remember seeing any signs or gates instructing people to not take skis.
Some places like Jay Peak (never been there, but read somewhere) take the approach of warning the public the glades are not sweeped, and you should ski with someone.
In my humble opinion, for vacationers especially, all these issues need to be clearly communicated to public, with little ambiguity. It's no light issue, "extreme terrain" that is "above" or "beside" lift-served areas.