My kids all know how to do laundry, but I do it. It is just easier for me to wash 3 large loads three times a week and get it done. They have to put their laundry away once it's done. They all have plenty of chores to do, but that is something I would just rather do myself.
When my youngest three were babies, the older three did their own laundry and one little's laundry. That worked for that specific time in our family, but it's more convenient for me to do it now.