Should Security Cameras Be Able To See Portions Of Nearby Private Property?

Use video privacy masks (see our tutorial). They are a common feature in cameras.

Check local laws for the legality of doing so. For example, our understanding is that in Austria, it is illegal for surveillance cameras to cover other's property (e.g., Austria’s First GDPR Fine Is For Video Surveillance).

Also, as a general tip, tilting the camera down will limit the camera's range and can somewhat restrict how 'far' it 'sees' into someone else's privacy. Good question, thanks for asking!

To directly answer your title question, it depends on how the property owner feels about it. Personally my neighbors are more than happy to have my gear keeping an eye on the neighborhood! Why not ask?

A general guideline is that even if the property is private, if the camera is only providing a view that is already available from public property (without a zoom lens), e.g. the sidewalk, it is likely permissible.  

so a driveway might be ok, a fenced backyard or secluded patio perhaps not.