The point of the license is for
1. preparing the owner to have the necessary knowledge to take care of the pets,
2. To confirm the owners have necessary budget, space, and time to take care of the pets,
3. To have the pet owners to sign the agreement that they shall never mistreat or abandon their pets, or face penalty which will not only revoke their pet license but also it comes with a large fine.
I guess if we let the shelters to do the license work, they can charge a small reasonable fee for issuing the license to keep it running. Much like driver's license.