The thing with (full) self-driving is that the edge cases are the challenge. Driving is the Pareto Principle really cranked up: (fully made up numbers) 2% of the driving represents 90% of the difficulty. And highway driving is a much simpler task to be automated than driving on a stroad, weird intersections, unprotected turns, etc.
I think we are a long ways off from full self-driving, and highway driving capabilities of current vehicles only address what is by far the easiest scenario. And even there those capabilities are limited from what I've seen.