You're twisting Johnson's words to say she didn't feel it; she was able to use a "whites-only" bathroom and didn't experience as much direct personal animus from her co-workers. That doesn't mean she didn't feel it, only that it didn't take certain forms.
But twisting that is also to miss the entire point of highlighting this moment in history: She was great, but not singular - she succeeded in large part because she had a tremendously lucky break others were denied. Much like a poor person winning the lottery doesn't create upward economic mobility, a black women getting a good job doesn't end racism.
(I already wrote about this at https://news.ycombinator.com/item?id=14482955 and I suspect there is some concerted effort to parrot talking points against the film as I've seen similar bizarre comments on many sites.)
But that's how movies work. You just have to let it go. If the movie makes you curious about what really happened, read the book.
The book is much better: more accurate and more historical context. (I do wish it geeked out more, but you do get a somewhat better idea of the science involved.)