Imagine you have a horse you don't care about, and it stops walking. For practical purposes it doesn't really matter why your horse won't walk anymore. You want to know one thing: what to do to get it moving again. If lazy means "now is a good time to dig in the spurs", then it's meaningful.
This is not a good way to treat people or horses, and not a nice thing, but it has meaning. Laziness means the spurs will still work. I don't use laziness as a concept because I don't like the mindset that comes with it.
Imagine you had a person with a broken ankle who wanted to stop, and you whipped them so they'd keep moving because you don't care. Does the master's lack of interest prove laziness is real?
This is not a good way to treat people or horses, and not a nice thing, but it has meaning. Laziness means the spurs will still work. I don't use laziness as a concept because I don't like the mindset that comes with it.