Applied inversely to bikes: Come on, these are bikes. You get on the bike, you pedal around, it doesn't take much time.

These devices usually have between 3-8 sensors inside (with wildly varying quality and quality control), run firmware that _usually_ has access to your WiFi or requires an app to run on your phone (security implications), and are meant to exist in your home for years at a time.

Good reviews which consider all those aspects take time and effort, even for simpler devices.