Same. Self-driving cars/vans would be brilliant for trailhead use. In 2016, hiking Trans Zion, we paid US$120+tip to get two of us from our car to a starting point about 60-90 minutes away. Earlier this year, my brother and I hitched three separate times to save 10 hours of road walking in a storm to get back to our car after Buckskin Gulch. We were lucky with the timing of each ride.
I've been deterred from hiking the Grand Canyon rim to rim by needing to either hike all the way back, or have two cars and add a 5-hour drive. Salt Creek in Canyonlands is another where a shuttle is a help, or crossing from The Maze over the river to The Needles (avoiding many hours of driving back).
Being able to call a self-driving car to affordably make these trips would be great.
The cell coverage isn't even required. If there is no driver waiting for me, I could affordably schedule the car in advance to wait at the trailhead until I arrive: all day if need be. It'd be no more expensive than having rented the car for the day.
If you had a self-driving car, you could let it take you to the beginning of the hike, and then let it drive itself to the end of the hike where you could take it home.
As an outdoorsman this is exactly what I am excited about with self driving cars. It has the possibility of making going even deeper into the wilderness more practical. A self driving car can take you to the trail head, go charge, and then go wait for you. With 300 miles of range you can go most anywhere.
If by "almost everywhere" you mean Europe or Japan, please compare population density. If most of the US had the population density of Northern Europe, or US northeast, or Silicon Valley, it would have similar almost-omnipresent coverage.
US West is more like Siberia, or Canada 100 miles north from the border. There are not enough subscribers to economically cover with GSM / LTE, except in cities and along major roads.
I'm talking about places like India or even Myanmar. To be fair India has probably a much greater population density than the US so maybe you are correct.
As a long distance backpacker I'd love to be able to get a ride to and from the trail at a reasonable price.
Of course, we'd also need better cell coverage.