Yes they are rare. The reason people like to take pictures of stuff like this is BECAUSE of their rareness. I've fed several thousand live rats to snakes throughout the years and I can think of ONE instance where the snake got bit, you couldn't even tell after a few days. I HAVE seen several baddly bitten snakes coming through the reptile rescue that I volunteer with, but that's because of people doing it WRONG. There are few common sense things to remember when feeding live. If you feed live food you should always supervise the feeding. NEVER simply throw a rat into the cage and walk away. If the snake is hungry, you can tell pretty quickly. If it's not hungry then remove the rat and try again some other time. The larger the rat, the more likely it is to bite so feed appropriately sized prey (no matter how big it is, an adult ball python never has to eat an adult rat)
Also for rat breeders, remember that aggression in rats in inherited. If you have an aggressive rat in your breeding racks, euthanize it and feed it off AND any babies that it has produced. I no longer breed my own rats but I did for many many years. By the time I stopped breeding I could take any rat in my rack and stick my fingers right in it's mouth without worrying about getting bit.
You're suggesting that you've bred rats so tame age trustworthy that they've not going to fight for their lives !!??