And kayaks too.
Tow bar: Not sure what others do without them. Furniture shops lend out trailers for free so that you can take your new sofa with you back home. I recently transported the materials for building my new front deck on a trailer. I tend to rent a trailer for taking things to the landfill/recycling facilities especially when renovating my home (and Norwegians do a lot of home renovation..). When helping young people move a trailer is all it takes. Etc etc. I used a tow bar at least five times a year for misc errands. (Now I have a Model S and have to leech on neighbors)
I am not sure why this is different and how e.g. US or German or French culture would be digferent.. I guess the alternative is paying others for delivery/disposal, doing less handiwork oneself, and (in the case of US) buying pickup trucks that in no way will fit on Norwegian roads and parking lots.
As a result, almost no cars in the US has a tow bar. Except pickup trucks. That don't really need them. Because you haul stuff directly in the truck.
In the OP's scenario, furniture, there are very few furniture stores in the United States that don't deliver. And if you happen to shop at one of those few, there are a number of ways to rent a truck for a day or by the hour: Home Depot, ZipCar, Enterprise, U-Haul, etc...
Perhaps higher minimum wage drives tow bar adoption...
Buying large things such as a sofa, lumber
Need to do this a handful of times per year, probably 5-6 on average. Everyone with a house does this.
Roof rack is for bikes/skis/kayaks.