I have recently noticed after completing the Companions quest "The Silver Hand" That some people do not attack the Werewolf form, whereas the general masses, (e.g. The guards) attack a Werewolf on sight. Is this Lore based or is there a genuine reason for this? I have also found that it is usually Wanderers who do not attack Werewolves, so maybe it could be related to that?
There is no lore based reason for this, it could just be that they aren't programmed to attack werewolf's on sight like the guards are.
Also if this was your first transformation this could be another reason why they didn't attack:
During the first transformation no bounty will be accumulated, no matter how many people are killed. It will not affect relationships with characters. Apart from miscellaneous conversation and the odd bounty or two, murders committed as a werewolf have no consequences, unless a quest-giver is killed, in which case their respective quest will be lost.
Also to be completely honest it might also just be a quality of life feature in Skyrim, because it would get kind of annoying if every moving thing attacked you while in beast form
4Guardians are protecting from threats and they see it in werewolves. Some people are careless, unable, unwilling, friendly, scared, "insert your reason to not" to attack werewolves. As to implementation in earlier TES editor there were flags and scripts: some actors have those, some aren't.– user135338Jan 25, 2018 at 15:05