The network architecture is different
A crowdsourced tag relies on nearby compatible devices to observe it and relay location. A cellular pet tracker includes its own cellular connection and sends data directly through the network when service is available.
That is why Fi and Tractive require active memberships for their cellular tracking functions. The fee supports a capability an AirTag does not replicate.
Battery life favors the simpler device
Bluetooth tags can operate for very long periods because they are not constantly running a cellular GPS modem. Cellular trackers trade battery life for direct communication and faster location updates.
Urban and remote environments change the answer
Crowdsourced networks are strongest where many compatible phones pass nearby. A loose dog in a sparsely populated area presents a very different scenario. Cellular trackers still depend on network coverage, but not on another person’s phone being physically close to the pet.
Cost comparison
The tag usually wins on recurring cost. The GPS tracker wins on purpose-built escape workflows. Decide which failure mode you are willing to accept before comparing purchase price.