That is absolutely true in probably 99 out of a 100 dogs, maybe even ten times that many, but there are exceptions. I know, I had one that was not trainable (as it pertains to food).

The breeder I got Tucker from warned me. He was 2 months old at the time, and she warned me that he was extremely "Alpha", especially about food, and she told me he always would be.

I ignored her. I too believed "it's just a matter of training". Most of the time that's true, but there are exceptions. Tucker was one. On his last day when I fed him he barked at the chickens and the burros because he could hear them from inside the barn, just like he always did. He could barely walk or see, I had to lead him to his food bowl, but he woofed his food down just like when he was a pup. Only I, and those he knew very well, could ever be in the same space with him and food. If he had even a bit of old bone stashed somewhere and anything got near it he go Tasmanian Devil on them.

To be fair to Tucker, he never bit anyone or anything. He would charge and bark, and if you didn't back off he would nip you on the heels, but he never bit and tore. If you didn't know him he'd scare the pee out you, I don't care who or what you were. If there was no food involved he was all love and cuddles.

I've warned people, way too many people, about him and I've heard "Don't worry, I know how to handle dogs" way to many times.

I'll say this too, a smart dog is just that. The idea that you have to spend half your life training a dog is ridiculous. Aussies, in general, are very smart. Tucker was no exception, he was also very strong willed. Some traits you just can't change or train out of a dog. You aren't going to train a Beagle not to chase a rabbit, and you're not going to train an Aussie not to run. At least not one that's worth a darn.

As I said, Tucker was exceptional in many ways, for example he knew his job was to guard and protect our livestock and the pasture we keep them in. He could have gotten out any time he wanted, but he never left it. And no other dog ever went in there for long. The only exception was females in heat. He even gave his food up for them. Shoot, he became a slobbering derelict whenever one was around, but he never left the pasture.

Annie, is of a completely different character. She's a bit alpha too, but not about food. With her, it's attention. She'll cut off our other dog, "Little Dog", when we go outside or come home and interact with them, but she loves Little Dog and in no other way does she try and dominate him.

Annie still will not follow me into the pasture though. It will probably take me a few more weeks to get her to follow me in there

If you buy a dog from a good breeder they will tell you about each pup you're looking at. That is a lesson I've learned the hard way. It has nothing to do with your ability to train a dog. Annie is spot on as described. If anything, she's a better dog than the breeder expected, but what they did tell me was accurate. So my advice is that if a breeder tells you a specific pup has certain characteristics you'd be well off to listen to them.