30 mph is almost 50 km/h. In most of Europe the default maximum speed limit inside of populated areas is 50 km/h.
Default meaning artillery roads like this one can and almost always do have higher limits than 50, but the defsult maximum suddenly becoming the minimum makes no sense.
A road that isn’t physically barricaded from foot trafic akin to a highway has no reason to have a minimum speed limit over 15 mph (30 km/h), if at all.
Also, they have to move off the road if space permits to let piled up traffic overtake, at least in Austria.