That's actually the point of the article - law enforcement does have access to tracking data, but the barriers to access are high.
By storing a user's data in an easily-accessible, unencrypted way the barriers are low enough that private investigators, stalkers, and other unsavory types have a similar level of access to someone's data, but with none of the legal hoops and hassles.
If stalkers and other unsavory types have unmonitored access to my computer and phone, them getting a file listing places I've been is the least of my worries.
You're a police informant. You're an undercover cop who didn't realise all this was accessible, but the organisation you've infiltrated just did.
Look, it's so easy to conceive of situations where someone's well-being is seriously impacted by having this location data stored so sloppily that it's almost not worth arguing about. Almost! ;)
By storing a user's data in an easily-accessible, unencrypted way the barriers are low enough that private investigators, stalkers, and other unsavory types have a similar level of access to someone's data, but with none of the legal hoops and hassles.