I knew cars drove ont he beach but was surprised to find it was a designated highway. There are speed signs on the land side of the beach and support people lay out signs for the airstrip when required. There is so much traffic it's just crazy and can get a little hairy. Quite an experience.
We do something somewhat similar where I live. We don't drive on our beaches but in winter, when the lake near us freezes solid, there is a designated road that drivers can use to drive across the lake. The road is monitored by British Columbia's road services, and obviously only open when the ice is thick enough. Still, without fail, each year someone will try to use the road before it officially opens, and their vehicle falls through the ice. I read about it in paper every year in the early days of winter.