Neither motion or object detection are really that reliable, in any system I've worked with. The norm in commercial systems has long been to record continuously and use motion/object detection/other classifiers to annotate the recording. That gives you the opportunity to search for events, like thefts, that may not have been detected by classification. You also have access to footage well before and after the detected event, which is often absolutely critical to answering useful questions (e.g. how did someone get past the fence?). Common patterns like 10 seconds before/30 seconds after just aren't always sufficient.

Unfortunately consumer devices are almost always cloud-based, where storage but especially upstream bandwidth are much more costly considerations, so recording only on detection has become the norm in the consumer world.

External triggers are also an important feature in commercial systems that a lot of open source projects miss---but Frigate isn't guilty of this one, it can receive triggers by MQTT, which is the same thing I do right now with Blue Iris. That's the big thing that has me optimistic about Frigate going forward. Because motion and object detection are so inconsistent, triggering VMS events based on access control systems and intrusion sensors is often a much more reliable (and even easier to maintain) approach.