Life360 is the default family location app. 66M+ users. Free tier shows real-time family locations and geofence alerts. Gold (~$14.99/mo) adds driving reports, 30-day location history, and crash detection. Platinum (~$24.99/mo) adds identity theft protection and roadside assistance. Your teenager probably already knows about it and has opinions. Works with Tile trackers for keys and bags.

You either already have Life360 or your kid's friends' parents do. 66 million users. It's the family location app the same way Google Maps is the maps app - not universally loved, but universally known.
Free tier: real-time location sharing for family members, place alerts (notifies you when someone arrives at or leaves school, work, home), and a basic map view. That's enough for most families.
Gold (~$14.99/mo): 30-day location history, driving reports (speed, hard braking, phone usage), crash detection with emergency dispatch, and crime reports for your area. The driving reports are why parents of teenage drivers upgrade.
Platinum (~$24.99/mo): everything in Gold plus identity theft protection, stolen funds reimbursement, and 24/7 roadside assistance (flat tire, lockout, towing). Bundling location tracking with identity protection - similar strategy to Aura.
Crash detection is the feature that justifies the subscription for many families. If someone in your circle is in a car accident and doesn't respond, Life360 can dispatch emergency services with their location. Peace of mind has a price.
Compared to Family360 (budget location tracking), Life360 has far more features but costs more. Family360 is "where is everyone." Life360 is "where is everyone, how did they drive there, and are they safe."
Compared to Bark (content monitoring), these solve different problems. Life360 tracks location and driving. Bark monitors digital content. Families with teens often use both.
The teenager perspective: many teens feel surveilled. That's a real conversation to have. The location sharing can be mutual (parents share too), which helps with the trust dynamic.