That is similar to the reason trackless trams are not economically viable. They are essentially just busses that are guided, but because of their precision the cause really bad erosion on the parts of the road where they drive. At least with busses there is variability on the parts of the road that are eroded and it affects the whole road more evenly
There are certain places/conditions where trackless does make more sense, however. Philadelphia still has several trolleybus lines active for instance, in addition to buses, trolleys, subway, el-train, and traditional rail.
My guess is that it works here because our roads turn to shit anyhow from the freeze/thaw cycle, so it's not adding as much maintenance burden as it would elsewhere.
