Drivers in the US are trained to yield to traffic before entering an intersection. They don't typically yield to traffic when exiting one. For pedestrians moving at walking pace, it's possible for them to see the pedestrian about to cross and yield since the pedestrian will be very close to the intersection.
A cyclist 20 to 30 feet away will not be in view of the motorist who is in the process of accelerating as they exit the intersection.
Making intersecton navigation more complex makes it more likely that someone will make a mistake.
There's usually no need to yield, traffic signals regulate that. The idea here is to create a more forgiving environment where making mistakes is less likely and less harmful. Thousands of these intersections have been build, here's some examples and some US context and research:
> There's usually no need to yield, traffic signals regulate that
Yet, the one example of a protected intersection I'm aware of in the US in Salt Lake City Utah[1] doesn't have bicycle specific traffic signals that regulate turning movements. They rely on motorists yielding to cyclists, or cyclists yielding to motorists. This causes problems when cyclists believe they have pedestrian style right-of-way when there's no law supporting that notion and it's not possible to see a cyclist moving at 20 to 30 feet per second in time to yield to them as they're about to cross the path of the motorist.
> American bike infra design and culture has been a failure on nearly every level
In what way? I live in a town with a major university and there are plenty of cyclists on the roads leading to and from campus as well as on campus itself. This is the case at many universities I've been to.
Also, as far as I'm aware, there are no protected bike lane installations anywhere around campus or in town, but we do have a nice rail trail.
A cyclist 20 to 30 feet away will not be in view of the motorist who is in the process of accelerating as they exit the intersection.
Making intersecton navigation more complex makes it more likely that someone will make a mistake.