Just as a guess, I would say that the instructions are generic. As you point out, the .45 ACP doesn't have a neck, so it isn't an issue for you.
The Classic Lee Loader will work fine in a .45 auto. I have loaded many thousands of rounds using a Lee Loader. And, the Lee Loader is a great way to start in the reloading aspect of the hobby. You start small, and can easily add some pieces, over time, to make the whole process more versitile.
The only thing you need to begin loading with the Lee Loader are powder, bullets, primers, cases, and a loading manual. In the future, you can add things like a hand priming tool to speed up the priming process. A powder scale and a powder measure so you can try different loads other than the ones you can do with the dipper. You can buy a dial caliper so that you can measure over all length as well as case length and the amount of taper crimp you are applying. Loading blocks. A little spray case lube would make things a little easier..............
Point is that you get everything you NEED with the Classic Lee Loader kit, but it can be expanded over time.
You know the rest. In the books you have read
How the British Regulars fired and fled,
How the farmers gave them ball for ball,
From behind each fence and farmyard wall,
Chasing the redcoats down the lane,
Then crossing the fields to emerge again
Under the trees at the turn of the road,
And only pausing to fire and load.