Ianal, but in texas, technically one does own at least some of the airspace above their property, though they are subject to federal/state/local laws and regulations .
It's obviously pretty gray, but, don't fly drones over private property of which one doesn't have permission.
I'm not a drone guy but reading the statue doesn't say much about flying a drone over private property, just taking photos of private property without permission
Quote:
AIRCRAFT TO CAPTURE IMAGE. (a) A person commits an offense if the person uses an unmanned aircraft to capture an image of an individual or privately owned real property in this state with the intent to conduct surveillance on the individual or property captured in the image.
Obviously, there's no way to know of the drone flying over ones property is taking video or pictures and there's nothing I can find stating the drone would be trespassing. In my non lawyer opinion, I'd consider it trespassing, but what do I know?