It generally isn't a problem because single readings are never used. They are always averaged over time and combined with other sensors. They also pulse their output and can detect interference and adjust their timing randomly to avoid it.
Think about how many devices manage to share unlicensed radio spectrum and how few cars will be that close together. The reason for having so many sensors is that if any one fails the others can make up for it.
Of course it will still fail from time to time, but less than a human.