Not sure what you call hobby drones. My guess is that with the more expensive hobby quadcopters it should be easy to get way to close to landing planes at 2000 feet. Basically at a busy airport you will have one plane every few minutes taking roughly the same path. So flying close to that path, for example to make video recordings of the landing planes will eventually result in a near miss.

Yeah, maybe my interpretation of what still classifies as "hobby" needs brushing up. I was only thinking of cases where flying the drone is the objective, not of cases where the drone is a tool to further another hobby. So I was automatically discarding altitudes where you'd no longer be able to see the drone.

Two things really changed because of the kind of electronics now available and because of the different community that developed quadcopters.

Electronics make it possible to equip models with cameras and real-time video links, making first person view flying possible and also making it possible to review the video footage you are getting. Electronics also provides those models with various automatic flying modes.

That results in a different community. The goal is no longer being able to pilot a remote controlled model.

The goal is now, using FPV to fly very complex patterns. Fly in woods, fly very far.

Or, use the quadcopter as a tool for filming. Because of the stability of a quadcopter, relative lack of vibrations (compared to a helicopter) and ability to stay at a fix point in the sky (which planes cannot do) they are ideally suited for filming from a position up in the air.