Enjoyable is when the road is open with no one blocking your way, no one on your ass, has nice curves and nice scenery. The passes in the Alps fit this bill, usually during the week. As for Autobahns, even the A2 or A3 outside of Zurich are more pleasant. But the A1 is a bore.
What happens in countries where trains run at night?
I watched a presentation of these guys at a conference last year... they have been on their idea for a good few years and are pretty much nowhere in my eyes. Perfect example of a technology that needs government support. I think their analysis of the problem is correct. Their proposed solution is a bit of a moonshot, but hey, why not stuy it... but implementation will only make sense if its done in a reasonable size, say Zurich region. It will only work if the pricing is competitive... or other regulations are in place to steer traffic. There will need to be a political will to actively move cargo traffic underground. It wont happen by itself as there are no economic incentives to do so.
Just as there are no private companies building motorways in Switzerland or new train tracks... would this need to be a decision to be made by the government. Unfortunately will this be extremly difficult as the different cantons across which the tunnel system would go... will never ever agree.