Vaccinations are not 100% effective. Some are closer to 100% than others, and some are closer to the other end of the spectrum. We try though. The reason vaccination even works is not because every animal in a herd is solidly immune to X disease - it's because a certain percentage of the herd is immune, generally 80% or greater, depending on living conditions/management - and this herd immunity protects the animals whose immune systems did not respond when they were vaccinated.
That principle applies to regions of the country as well - herds that are not vaccinated are generally protected by herds in the area that are vaccinated. Those of you who don't vaccinate are just lucky - that's it. Sometimes you get unlucky - such as in the case of ranchers who have disease outbreaks in their herds when no one else's herd is affected. That's when you know who vaccinates and who doesn't...
That principle applies to regions of the country as well - herds that are not vaccinated are generally protected by herds in the area that are vaccinated. Those of you who don't vaccinate are just lucky - that's it. Sometimes you get unlucky - such as in the case of ranchers who have disease outbreaks in their herds when no one else's herd is affected. That's when you know who vaccinates and who doesn't...