Do you mean people underestimate how steep the gradient is, or they don't know it at all?
It seems kind of dubious to me that "everyday" people don't understand that land in cities is worth more than land in suburbs. It seems very transparent that you get a smaller lot size for the same price.
Both. They do understand that it’s worth “more” in the city but they vastly underestimate the magnitude, and they vastly underestimate what that means in terms of where the total bulk of land value is concentrated, and therefore what the distribution of winners and losers will be in any tax shift scenario.