Unless you are referring to self-driving cars, then what you really mean is: drivers will hit them with their cars. Anyone who is unable to drive in a 3.5 metre lane without hitting things at the sides should not have a driving licence. How do these people avoid hitting kerbs? If that’s you, then for all our sakes and yours, send your licence back to the DVLA at once.
In any case, if people who are driving can’t do it without hitting things, that’s all the more reason for them to kept separate from people on cycles and people on foot. Better that a few recycled plastic wands and orcas get smashed up than the flesh and bones of human beings.
It should be remembered that the wands are not there to protect people on cycles; it’s the orcas that are there to protect them. The wands are there to protect the orcas from being hit by incompetent drivers and would not be needed if there weren’t so many idiots driving motor vehicles.