For someone who has never used an
ecv before, using one at WDW may be very intimidating, especially if the person doesn't drive a car. My DD recently got a power wheelchair, which looks very simple to drive if you are watching someone who is familiar with it. When I sat down and tried it, I found I would need some driving time to get comfortable.
I have suggested before that people try out an ecv while shopping. Stores like Target and some grocery stores provide them for their customers with mobility needs. Most people who would possibly use one at WDW would also benefit from one while shopping, so don't feel shy about using one; that's what they are there for. The ecvs at WDW (and the outside rental ones) are a little different than the ones stores have, but the general principles of driving it are the same.
One you get to WDW, practice a little with the ecv before going out in the "World". Get a feel for how it turns, how fast you can stop it, etc.
And, if you don't think an ecv is for you, don't feel bad, some people don't like driving a car either. That's one reason they rent wheelchairs.