The ABC pointed out the correlation between educational achievement and tendency to vote one way or another (source below).
However, rather than simplify the matter as Waleed did, we should consider that: -Cities like Sydney and Melbourne require a higher income (relatively) to live in, meaning that their residents will tend to hold higher paying jobs, which naturally require a higher level of education. -Anecdotally, the Yes campaign was strongly concentrated in these cities. For instance, there were Yes stickers on street posts and tram stops. Shop/retail fronts, such as those of banks, had symbolism indicating their positive view on Indigenous issues. Outside the cities, there was little fanfare. -People with high educational achievement tend to value their professional relationships and are employed in organisations that declared their support for the Voice. These people would be less likely to want to damage their reputation among their colleagues and in their workplace. In contrast, people with low educational achievement have different ways to build and maintain a reputation with their peers. -Many professional groups supported the Voice, which encouraged, at arms-length of course, their members to consider their view point. -Indigenous people frequently live in lower socioeconomic areas. Their non-indigenous neighbours interact with them often. This allows the residents of such areas to compare their neighbours to the dressed-up, cookie-cutter Indigenous personas portrayed by the media. In doing so, it neutralises any appeals to emotion by the media. Example: They might see their Indigenous neighbours throw their litter on the land that they are supposed to have a spiritual connection with.
Therefore, I think it is important to see the lifestyles and experiences of the highly educated as being the reason behind their tendency to vote Yes, rather than simply the fact that they are highly educated; and vice-versa.
