A blindfold allows someone to be in close proximity to the person while also retain g visibility and communication with that person and other people (e.g. the driver).

If you lack out a special cabi area for a vehicle, either you are leaving them to their own devices in that area, or limiting the senses of your own staff you put in to watch them.

Finally, it's just a lot more expensive and cumbersome to have a large piece of machinery like that, and more likely to fail. What happens if the engine fails? Do you need a spare now? Using a blindfold as backup means that a blindfold is sufficient, so just use it and any vehicle now works.