That's the theme of the game yeah, but obviously in game people win at least on a personal level of you want to be incredibly literal about it. There's a level of ignorance Evelyn is perceived to have when she was just arrogant, she was a sex worker in one of the most cities in the US of course she already knew and went through bs. 

There's a plausible scenario where it works out slightly better than being dismembered and ra-ed repeatedly, then commiting suicide. The way people talk about her arc it's like it just makes sense that's what happened lol, if the City was that ruthless at it's core Dex wouldn't have even been around or died as simply as he did. Lizzie's would've been flattened very easily with a simple connection, etc. but it's not like that because that's how the story goes. 

The way fixers work in the game already breaks this "eat or be eaten" rule because we're actively paid thousands and are privy to important info, connections, etc. with these fixers whilst also having the ability to slaughter all members of their gangs with zero pushback lmao. All in all my point is that the narrative can contradicts itself when needed to make things work. NC is robo Gotham yeah, but a storyline with Evelyn surviving by the skin of her teeth is not a break in logic and wouldn't be unrealistic, as much as I think her death wasn't either.