While a lot of us are using these as anti-theft devices, that isn't Apple's intent, so performance will be less than ideal.
That being said - the thief will likely get the notification when they arrive at a known location (eg their work or home as defined in their iPhone) - so, maybe they're within 30 minutes? (but, think about it - a thief will have the location of their "chop shop" in their contact card as their work?)

. So, unlikely to get the notification that they're being followed in a very timely manner (and if they have an Android phone, not at all).
So, yes, you can use AirTags as an anti-theft device, but your window to realize that the item has been stolen and act on it can be shorter than you'd like.
I would think the 3rd parties that are licensing the access to the FindMy network are likely getting a different experience - as the entire point of that licensing is as an anti-theft device. Certainly within Apple's prerogative to give them a different experience. AirTags are just too portable/transferrable to get that treatment.
Edit: To clarify - I'm talking about the bicycle manufacturers that have it built in - but I could see the manufacturers of the head units for cars that support CarPlay also building it in, to leverage Apple's FindMy network for stolen vehicle retrieval (and, of course, finding your car in the mall parking lot)