I really don't have a lot of background on cluster munitions; it only really came into my perception in response to the controversy over the US providing them to Ukraine. As I understand it, the controversy is because they often don't all explode reliably, and unexploded munitions can then explode months or years later when civilians are occupying the territory, making it similar to the problems caused by landmines.

In an age where things like location trackers, radio transmitters, and other such local and long-range technology to locate objects are common place, what's stopping the manufacturers of these munitions from simply putting some kind of device to facilitate tracking inside each individual explosive, to assist with detection and safe retrieval after a conflict? I get that nothing is a 100% effective solution, but it seems like it'd solve most of it.

Can someone with actual knowledge explain why this is still a problem we're having?