You're describing two completely different types of socialization though.
The first two are examples of a single children missing out on key childhood socialization "training" that will help them as they grow older. The third example is of leaving many children unsupervised to do as they will.
Sure, kids do need to learn to socialize in large groups, but leaving them unsupervised on a self driving bus is a recipe for disaster, and not at all the same as kids being home schooled or skipping grades.
The first two are examples of a single children missing out on key childhood socialization "training" that will help them as they grow older. The third example is of leaving many children unsupervised to do as they will.
Sure, kids do need to learn to socialize in large groups, but leaving them unsupervised on a self driving bus is a recipe for disaster, and not at all the same as kids being home schooled or skipping grades.