My interpretation of the difference between technical and recreational.
Recreational is any dive where free ascent to the surface is possible at any and all portions of the dive.
Technical is any dive where free ascent is not possible due to a virtual or hard ceiling. A virtual ceiling would be a deco obligation. A hard ceiling would be like in Cavern or Cave Diving, Ice Diving, Wreck Penetration, etc.
Now, most wouldn't agree that Cavern Diving is technical. I'm kind of on the fence myself to be honest. But when I teach (and the mentors I surround myself with) cavern diving, I'm teaching it as if everything went wrong that could go wrong, can you still survive. Yes. Well, not literally, because if a submarine fired a torpedo in the cavern, you're pretty screwed. Technically it could happen, but not very likely.
First of all, I agree with your definition on the difference between technical and recreational diving. When it comes to whether or not cavern diving is technical or recreational, I think we are straying into what I earlier defined as that middle path between the two. To understand how I see it, remember that quite possibly the majority of recreational divers have gone through short swim throughs and entered prepared wrecks without technical training. I still think those are recreational dives. In those cases, they have made the judgment that although they will not at that point have direct access to the surface, it won't take them very long at all to get direct access to the surface. As long as they don't go into blind panic, they should still be able to get out of the overhead and go straight up without difficulty.