@JaneAir - You're right, safety is important. However, I think it's extra important to get an electric wheelchair the user can actually operate!
As the article pointed out, people who use electric wheelchairs have a varying range of mobility. Some can walk a little bit, while others are partially paralyzed. Obviously a person who is paralyzed will need a different kind of electric wheelchair than a person with some mobility.
Anyway, I had no idea that there were electric wheelchairs that could be operated by head movement. I think this is really cool and of course makes total sense! Obviously someone who can't move their arms would need another way to operate an electric wheelchair.