To be fair, she’s apparently been around more or less for the entire length of human civilization. She’s lived under lots of different economic systems, and from her point of view the Federation was basically founded yesterday. Skepticism makes sense in that context, even if she generally approves. We the audience know that by the time of TNG, DS9, and Lower Decks (I have not watched enough Discovery to know if the far-future Federation is still portrayed this way), the Federation has if anything only gotten more post-capitalist, so I don’t know that we’re meant to read her skepticism as wise. I mostly took it as her being defensive and a bit flippant.
Trains don’t cover literally every single use case of a car, better keep expanding those highways!