Yes, riding your bike in an urban area is often more or less as fast / convenient as driving. However, driving at 70mph vs biking at say 15mph, the time difference adds up very quickly once you are out in open country.
Not to mention that there is very well built infrastructure for driving, while biking often means going on that same infrastructure with a 50mph difference between you and the rest of the traffic. Basically if you are riding on a bike on a highway, you need to act as if you were invisible and expect that cars may actively try to kill you.
[1] https://www.google.com/maps/dir/Nevada,+Iowa+50201/Ames,+Iow...
also my two cents: it's dangerous as all heck doing anything but driving on those roads. I almost got hit by a friend of mine who was texting and driving while I was running about 30 miles from there out in the country.
It's insane how little bikes (or pedestrians) are considered compared to here in Sweden.
You don't need a truck, but you definitely need a car (with four wheel drive in many parts).
There are millions of people who live in places that require traveling on high-traffic busy roads to get from point A to B. These roads almost never have a bike lane (bike lanes do not exist outside of large cities). On many roads I drive on (speed limit 55 mph) there is no shoulder. Combine that with roads that have sharp curves that prevent drivers from seeing more than 25 meters ahead... yea, I would not bike with a kid with me.
In the case you mention, airbags are a pretty good reason. Also distance. And disabilities.