Years ago I took a Suzuki piano teaching course. Although I only include selected elements of the method in my teaching, one belief I acquired is that when a young child takes lessons, the teacher is the guide one day a week, and parents are the guide the rest of the week.
I teach with a lot of precision in order to put my students on a path towards success. Young children who are just beginning to figure out how their bodies work while getting their first exposure to music cannot be expected to remember a lot of details when they return home after a lesson. For that reason I expect a parent to be at the lessons and to actively assist in the practicing when children are in kindergarten through second grade. After that, it is still very helpful to have parents at lessons and at least nearby in practicing, but children can gradually assume more responsibility.
I will often have parents sit at the piano so that I can show them things directly; they can guide their children better if they have first-hand experience.
As a parent myself, I fully understand the trials and tribulations of getting young children to practice. I suggest that parents who are considering piano lessons for their children try lessons for a month (you must have an instrument to practice on for that month). Try to establish a very regular and predictable practice time. If after the month, you decide to continue, commit yourself to regular lessons for a minimum of two years. The reason this is important is that there will be ups and downs in the process. Children learn a great deal about the value of perseverance and the joy of music by working through challenges to make new discoveries.