My research shows that the International Symbol of Access was chosen by Rehabilitation International, a federation of 145 organizations in 82 countries that conducts programs to
assist people with disabilities work for prevention, rehabilitation and integration. In 1968, the design by Susan Koefoed was chosen and is still used today.
The designation, International Symbol of Access, helps to give a better perception of what the symbol accomplishes. It's not only about designating a parking place, vehicle or bathroom; it's about plainly marking access routes and approaches, too. This symbol is never confused with any other symbol. It's easy to spot. It works. However, perhaps something like this update is in order: