It’s not actually illegal anywhere (in the US) for a non-vet to administer the rabies vac. What’s illegal is having it shipped to many states (but not all).
Wha IS “illegal” is the recognition that the horse is vaccinated if your vet doesn’t do it, and that’s in all states. So if you DIY, and there’s a rabies exposure situation, your horse is legally unvaccinated, and then you have to deal with all the repercussions of quarantine and all that stuff
I get it that some have enough horses, and/or enough special situations that having a vet do all the vaccines is very $$. For those who already have a great VCP with your vet, and they’re quite ok with your DIY, go for it.
Now that many of the common antibiotics have been moved to Rx-only, which means you HAVE to get then through a vet, people who would only see their vet for vaccinations and who are just being cheap to save $30 or so, they really need to re-think that because their vets aren’t going to just send you an Rx (or sell you) an antibiotic like Tomorrow for thrush, when they haven’t seen your horse in 6 years. It’s already an issue that so many people can’t get even local vets out for emergencies because they haven’t had their vet out in forever for any sort of wellness visit.
I pay my vet plenty over time and have used her for over 30 years. She still does all vaccinations, AND she has no problem leaving me things to administer later so as to avoid another farm call