I must take exception to your characterization of dog license tags as a non-numismatic collectible.
Dog license tags are included in Tokens and Medals A Guide to the Identification and Values of United States Exonumia by Alpert and Elman.
I met William Bone at the National Token Show in Omaha and include his tokens with my tokens of numismatists.
License tags represent the payment of a fee or tax good until a future date. Similar items include cat license tags, cattle tags, and horse tags. While full size auto license plates are not included in the Alpert / Elman book, miniature auto license plate tags are included. Also not representing the payment of a fee are military dog tags and other personal identification tags like key tags.
The field of exonumia is very vast and there is a collector for everything.
... and don't forget Slave tags. It's a slippery slope trying to define where numismatics and exonumia begin and end. I like the "represent the payment of a fee or tax" definition for tags and can see where some might include this class under the broader term of exonumia. Another method of classification is "method or means of manufacture", and I personally feel better about including dog tags because of the similarity of many of them (particularly the early ones) to tokens and medals. The designs and engravings are often delightful and make for a great collectible.
How do our paranumismatists on the other side the the pond classify such items? Are they considered paranumismatic?