I'd say that's true, Herefords are like any other breed some are extremely docile, some are at the total end of the spectrum and others anywhere you in between.
It is my belief that disposition is a multifaceted situation. Some individual cattle are just genetically prone to be more wild or aggressive than others.
Management has an effect too, if cattle are used to seeing people and having a fairly positive experience when people are present then they generally are easier handled than when only dealt with on rare occasions or dealt with roughly.
Environment plays a role too. If cattle have to contend with predators then they are more cautious and on edge.
Back to Herefords, I've had some really calm ones and some real skittish ones too. One bull I used was kinda flighty, but manageable, some of his daughters were crazy, Have one right now that we have to hide out of her sight before she will go through a gate, while the rest of the cattle will walk right through with me standing at the gate after opening it.