The QLine is a streetcar and most streetcars run along the curb in mixed traffic. The thing is, is what people wanted, and what the city wanted to do was light rail. The QLine is a very typical streetcar, basically a modernized version of the streetcars from the 1950s. Light rail is like a hybrid between streetcars and subways. They use a different style of vehicle, and are longer and carry more passengers, travel faster, have more doors for passengers quickly board with. Light rail lines may have some portions mixed with traffic, but most of the route will have dedicated lanes or even have sections which are elevated or underground. In the mid 2000s, the private group wanted to build a streetcar to New Center and the city wanted to build a light rail line to 8 Mile. The city strongarmed the private group into joining the city's project, but the city's project was cancelled basically because of the city's finances, and so the private group went ahead and built their streetcar.
Portland created one of the first "modern streetcar" systems, and this is what many streetcars including the QLine are based on:
https://www.youtube.com/watch?v=pKSt8NA1ees
For Hudson's, since you mentioned it I went back and looked at the rendering posted in a 2020 article showing the structure.
https://www.gannett-cdn.com/presto/2...pjpg&auto=webp The upper parts of the tower have the long flat wall-like "columns" characteristic of concrete. You can't tell what the bottom parts of the tower are in the rendering, but I have a separate section drawing [[I don't have a link handy) which clearly shows the steel beams in the lower part of the tower, but not the upper. So this is how it was planned to be.