You’re over simplifying the first, and conflating the other.
The MLK protests made change on the back of decades of campaigning together with multiple organisations applying different types of pressure and activism for the same goal, including president Kennedy, and several PR disasters for the opposition.
As for the 2001 attacks, what would you say was their political goal? Was it fulfilled by those attacks? If not, I’d scratch that up as a failed attempt.
Street protests are one of several necessary activities for a change movement. They can help build awareness and let off some steam, but need considerable mass to affect change on their own.
More change happens when paired with organised political action, strikes, obstruction, PR and ofc violence/terror.
The trick is to coordinate the sides towards the goal. Only street protests or only terror won’t do anything, but pulling together you did get 8 hour workdays,or more recently grain import regulations (in Poland).
Then again, a million protesters over three months, including transport striking and uncoordinated violence, did not affect the French pension age.
“Nuh uh”