Years ago I took a Suzuki piano teaching course. Although I only include selected elements of the method in my teaching, one belief that 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 quite a lot of precision so as to put my students on a path that sets them up for success. Young children who are just getting their first exposure to music and figuring out how their bodies work cannot be expected to remember details of how we worked when they get home. Therefore, I expect a parent to be at the lessons and to actively assist in the practicing of children 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 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 (Know that you must have an instrument to practice on for that month). Try to establish a very regular and predictable practice time during that month. If after the month, you decide to continue, commit to yourself to continuing regular lessons for a minimum of two years. The reason this is important is that there will be ups and downs in the process. The joyful successes at the end of a challenging time teach children a great deal about value of perseverance.