Car costs money, gasoline costs money. How do the drivers need the riders? Sounds like just plain stupid to me. Money is a good invention and tool, why not to use it.
Edit: realized that this allows the drivers to use express lanes, which are common in US. (Don't have those in my country).
https://en.wikipedia.org/wiki/Slugging
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[...] frustration over failures of public-transport systems and high fuel prices, led to the creation in the 1970s of "slugging", a form of hitchhiking between strangers that is beneficial to both parties, as drivers and passengers are able to use the HOV lane for a quicker trip. While passengers are able to travel for free, or cheaper than via other modes of travel, and HOV drivers sometimes pay no tolls, "slugs are, above all, motivated by time saved, not money pocketed".
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It would have taken you less time to read that than to write your comment.