Madame CJ Walker started a business...

I personally believe so. Tiana and Charlotte met as kids and kids usually aren't fully immersed into racism until about the age of seven, in my humble opinion, so yeah, their relationship is rather plausible.

It would be extremely hard, but I think she could pull it off with the right amount of luck, skill, charisma, good marketing, etc.

Most well-to-do white people were extremely racist and classist though, didn't mix with "the help" or people of different races; or at least didn't do so publically so as to avoid social scorn. Even if Lottie and Big Daddy were nice, I'm not sure they could get away with being so friendly with folks like Tiana and Eudora without losing a lot of points with their fellow rich white peers, and social pressure would most likely force them to stop before they even started.

Besides, the film DOES show some of the struggles she faces trying to get her restaurant. Her (black) peers pretty much saying "You're aiming too high," her mom encouraging her to get married and start a family instead, the racist white bankers either made up a mysterious higher bidder so they'd have an excuse not to sell her the mill, OR they choose to sell it to the (presumably) white guy over her. They even tell her to her face: "A little woman of your... background would have her hands full trying to run a big business like that. You're better off where you're at."

At least the film acknowledges that she would face race and gender-related trials and tribulations in pursuit of her dream, even if they just use subtext to explain it.

HOWEVER, with Lottie, there is absolutely no acknowledgement that a girl of her race and class would be very unlikely to befriend someone like Tiana, or at least not without social repercussions from her wealthy white peers. There is no acknowledgement in the film that white people tended to look down on black people, rich people tended to look down on poor people, so Lottie being friends with Tiana would be considered highly unusual at best (we're talking Belle getting flack for reading books, here), socially repugnant at worst.

Like I said, at least the business problems are acknowledged and hand-waved in the film, while the unlikeliness and consequences of an inter-class and inter-racial friendship is ignored entirely.

But it's also weird how she opened her restaurant since she is black.

Tygers_Eye convinced me.

I really don't know...

Same as Alexandra.

though I don't think the movie actually touches on racial issues much. they don't mention it once; it's vaguely implied, but from the way they went about it it sounded more like classism. And Eudora encouraging her to raise a family isn't related to that. Homemaking wasn't just accepted back then, more than now in our age of super careerwomen, it was what most women wanted and just what was done. Eudora probably really did just want to see some grandkids soon too. Older people always tell their kids and grandkids that!

as someone pointed out, CJ Walker did start her own business, and there's some black inventors too, so that wasn't impossible, but social boundaries usually exceed things like this. even a racist might use a black person's business if they think they're good enough, but befriend them? unlikely. actually go out of their way to help them? even less so.

Both, I would say. I agree with Dylan, though.

Especially since it was a WHITE man's world in the time that this was set

Both.

Racism was very rampant in the 1920s! And Predominantly
Rich White people weren't colluding with people
who were lesser than them.
If a Rich white person was "friends"
with a person of color, they would be
considered a threat to the Pro-White society
and either killed or imprisoned.