They are not HARD to use but it does take getting used to. You need to get your mom to use them at the grocery store and Wal-mart it is the best way to get used to using them, be sure to find a bit of the store not too busy where she can practice backing up, turning around etc. Wal-mart is good for trying to maneuver in tight places.
Be aware that the scooters in the parks are bigger than those that you can rent off site.