Curious why you think trucking would have a bigger societal impact? As to why Google et al. are aiming for passenger vehicles, there about 4 million semi trucks in the US and over 290 million passenger vehicles.

And whats the economic value of 1 mile driven per truck vs passenger vehicle?

Cheaper truck transport also opens up more cost competitive manufacturing, factory placement. Which will be highly deflationary.

In a remote work world a large percentage of the workforce only has to travel for discretionary, not economic reasons.

Anyway, normalizing for cost-benefit, trucking clearly comes out ahead

For a venture, you want the value that you can capture to drive direction, not all the externalities and I think with trucking that's small.

It makes sense for the US Gov, just not for Google.

It’s possible they are asleep at the wheel

Waymo is doing trucking too. It's probably a 98% overlap with the skills their driver (the Waymo software) needs for driving passenger vehicles. Automating driving is so difficult, it's a mystery why anyone thought all but the largest, most advanced, and best funded software companies could succeed.

Because maybe it's not vastly easier to accomplish

With tons more liability per accident...