Something which really confuses me

People when they talk about the South and its history seem to have this conception that there were somehow no laws separating blacks and whites for decades.

Let's examine how this logic works:
1) What was Rosa Parks (and the subsequent Montgomery Bus Boycott) about?
2) What were lunch counter sit ins about? (why did people doing them get arrested?)
3) Why did Martin Luther King and other civil rights demonstrators or leaders keep ending up getting arrested? (what laws were they breaking... on purpose?)
4) Where did all those "colored only/whites only" signs come from? Did people just like putting them up? What happened if someone ignored them?
5) When/where did legal bans on interracial marriage persist longer?
6) Why did federal troops have to be sent in when schools were integrated (despite a Supreme Court ruling?)
7) What was the poll tax?

I can see a couple places where people might be confused.
1) Redlining is a different process of discrimination than official state mandated housing discrimination. But the latter also existed.
2) Interracial marriage rates are still extremely low in the South relative to the rest of the country and there are other somewhat more or less ominous indications of persistent racism (Obama is a Muslim or Obama is a Kenyan both are more common beliefs among white Southerners for example).
3) Why did federal troops have to be sent in when schools were integrated (despite a Supreme Court ruling?) (this one probably cuts both ways I should think, since most people don't understand Supreme Court rulings often involve pre-existing laws being overturned). Also: current Southern schools rates of integration are usually some of the lowest in the country.
4) Selma, police brutality, and various extralegal reprisals by KKK and other terrorist organisations. It is one thing to establish laws which are unfair and uncivil and arrest people who violate them, it is quite another to enforce them with a zeal and a brutality that suggests other nefarious motivations and to use extralegal vigilante force but ignore it by official laws.

But despite that confusion, it doesn't seem to me like it would make much sense to have thousands of marches and sit ins and protests involving many thousands of people if all they were agitated and aggrieved over was other people being racist assholes. If they were racist assholes with laws written to enforce a state of segregation and mandated discrimination and specifically and intentionally written without the input of the people being discriminated against, then perhaps it would be easier to find large numbers of very annoyed people willing to march and to otherwise act in solidarity to defy immoral and uncivil laws.