Why do we vaccinated animals over and over but not people?

Factual Questions
#1

I’ve been reading up on animal vaccinations, especially dogs.

One thing I keep reading is that the whole idea of multiple vaccinations (ie, rabies every 3 years, parvo every year or two, etc) is coming under suspicion. I don’t want to debate that, as it’s clear to me that the debate is up in the air still.

What I do want to know is why we vaccinate animals multiple times to begin with, but humans tend to get only one vaccination. In rare cases - like tetanus - it might be repeated every ten years or so, or whenever you step on a rusty nail.

Are animal vaccines different, making them not last as long? Or do they figure that there’s so many animals out there that aren’t vaccinated that the communicable diseases are stronger/more common? Or something else…?

#2

Human preexposure rabies vaccine requires booster shots, just like animal rabies vaccine. People exposed to rabies are supposed to be tested every six months, so it looks like the vaccine lasts longer in animals than in humans.

Essentially, some vaccines confer long-term protection, while others only provide protection for a few years. I would assume the animal vaccines tend to wear off.

#3

Pretty sure humans get a few booster shots through the first years of life. We’ve had our daughter in several times for shots and I don’t think they were all for different things.