The government lied to everyone, and some believed it. You'd seemingly like to make a villain out of all white South Africans, but that's not helpful in any way - many, like myself, were born into apartheid and struggled against it. So were my parents - they had no part in making those laws, and yet were born before the Union was established. It's easy to miss what it's like to try to counteract a regime - you and your loved ones will suffer. The populace did not wield the power of transformation itself, it was international intervention that allowed it to happen.
Were some complicit? Yes, obviously. Did many know? Probably. Was it the majority that supported a status quo for some time? Yes, but not without being manipulated. It was standard education that there were 'grades' of people for most of the 19 and early 20th centuries, and in South Africa this was redoubled. Narratives like 'black people are the result of the snake and eve' were common. I've spoken to many older people who are horrified at what they believed. It's incredibly hard to escape a bubble when it's all you hear. State TV, state sanctioned news, international sanctions mean you didn't ever hear how SA was seen internationally. The TRC was asking people to recognise what it saw, and what many others saw - that evil is banal, and within us. It deliberately did not pursue further actions against those that were not directly involved in harm, or who ordered it.
You have taken 'large numbers' and seem to have interpreted it quite liberally to mean 'the majority', and then further concluded that there is then some obvious flaw in their moral character. I could say the same of the US forever wars and destabilisation, but would it help? To accuse and paint with that shame every citizen?
[1] https://en.wikipedia.org/wiki/1992_South_African_apartheid_r...