I can tell that’s the case without looking at any stats, I’ve been monitoring AMBER alerts here in Canada for the past 4 years, and 100% of the cases are just parents taking their kids back, wasting a whole system resources for that ..
AMBER is generally a waste because it's oriented towards kidnappings by strangers. But kidnappings by parents aren't always no big deal: parents sometimes lose custody because they're a serious risk towards their children.