The empty seat problem in private cars is more of an issue with personal safety and the broad increase in crime over the past fifty years. Technology should help here, but the reason low-tech hitchhiking has all but disappeared is that it is not safe for the rider or the driver. This didn't used to be the case-- the boomer generation hitchhiked across the country to college, for example.
There hasn't actually been a "broad increase in crime over the past fifty years" in the US; consider http://www.disastercenter.com/crime/nccrimn.htm which shows that, in North Carolina, violent crime in general has nearly doubled over that time, and robbery has increased by a factor of six, but murder rates have halved. A similar trend is seen in San Diego http://www.sandiego.gov/police/stats/ — violent crime has quadrupled, robbery has barely doubled, and murder has halved. Furthermore, these overall trends have been far from monotonic; the crime peak in 1990–1992 is far worse than anything we've seen over the last 20 years.
And there are lots of countries where low-tech hitchhiking is very much alive, and crime is much higher in most of them than in the US.
I think the real reason for the change is economic: as people in the US got much richer, they preferred the safety of private cars, airplanes, and other public transport, to the cost savings of hitchhiking.
Regardless, that's a problem of information. You want to know if the person you're riding with has a record of trying to rob or rape previous drivers or passengers, or even leering at their tits.
It's more of an issue of the American perception of danger, and the anti-hitchhiking laws passed as a result. Lots of people still hitchhike all across the US.
If I were going to pick up random strangers to disrupt my otherwise-peaceful me-time alone in my car, it'd have to have a big incentive, and being able to split the money I pay for gas just ain't it. Being a taxi driver is a sucky job, and I don't wanna do it in my spare time for cents per mile.
"Tolerance" is a noble concept in some sense. It means I respect the right of others to be stupid and annoying in the abstract, not necessarily in my passenger seat.
As for "noble concepts", well, there's the kind of tolerance that's a "noble concept", and then there's the kind of tolerance that's an actual description of how some people behave toward other people, some of the time. Like, how Argentinians behave toward children, that people from the US don't. Or, for that matter, how Argentinians behave toward US tourists.
Turns out that there are real benefits to turning down your annoyance and smarter-than-thou attitude and digging folks who don't shop at the same supermarket you do. I can't always do it, but I'm glad when I can.
(By the way, when you complain about how awful it is to have to talk to someone who's stupid, you should consider how that would sound to someone who's a lot smarter than you are.)
The bigger story is Craigslist ridesharing, and carpooling startups like Zimride, PickupPal, Carpool to School, and CarBuddy. In countries like the US, where the average car has something like 5 seats of which 1.2 are full on any given trip, taxi and bus services are only able to exist at all due to an market failure of truly mind-boggling proportions.
Any time you drive anywhere in a city, there's probably a reputable, trustworthy person or two within a couple of blocks who wants to go close to where you're going, at the same time. If you knew about them, you could go pick them up (the 80% of the time that you don't mind driving an extra couple of blocks), and magically your cost of driving would drop by half or two-thirds.
It's a good deal for the passengers, too, compared to a cab. If your cost is 50¢ per mile, they might pay 25¢ per mile, compared to some 90¢ per mile in a taxicab; and of course, as with Über, they can just walk outside as the distance meter on their phone approaches zero.