I feel like it’d be an uphill battle to say you can’t use it to find e.g a car in an Amber Alert, or actively escaping. But I don’t know, do they already get warrants for that kind of thing?

At least retention periods should differ

I like it. But it's going to rule out some very useful searches. (Where was that car in the 48 hours before the crime was committed, and in the 24 hours from the crime to the warrant?) So there is going to be great pressure against this idea.