Somewhere here there is a thread where they took the Mom/MIL to
Disneyland and when the husband and his Mom came out of a restaurant, she mistook an
ECV for hers and left with it. Soon she realized her mistake and went back to the restaurant where the poor other lady was very upset that her scooter was "stolen". So, obviously this can happen by mistake, which is why you should always put identifying objects on yours to prevent this. It would be very rare someone would try to steal it, but they might mistake it for theirs and take off with it. The person who wrote about it was very funny and a good writer, wish I could remember the thread.