In watching HGTV with children and studying suburbs and housing, I have several ideas of what kids learn while watching the network’s programming.

To start, HGTV shows are built around emotional stories about home repair or home acquisition. There is a regular narrative arc where people want to improve where they live or find a new place to live, they face some obstacles along the way, and then they are successful by the end of the episode. The shows are filmed, edited, and scored in such a way to create such a positive emotional payoff. The shows suggest they are helping people find happiness.
All of this weds the idea of homes with happy feelings. The shows are upbeat, the search for a better homes a success, and viewers have a positive resolution. HGTV has very few negative outcomes or unsuccessful work. The characters rarely talk about emotional distress, financial difficulties, and difficult family relationships. Only rarely do people not find what they were looking for and even then the ending is cast as a successful change in focus. Any obstacle is easily overcome.
In sum, HGTV is an emotionally positive network. I could see why parents or families might feel comfortable having kids watch such happy outcomes. A new or renovated home is good for the well-being of the resident(s) as well as the viewers.