So where I live (US) we have carpool lanes - not on the highway, but on regular commuter roads, city blocks, mostly commercial but also some residential areas. These appear on the right-hand lane. You know, the turning lane, where other vehicles are turning onto the road, or turning off of it, where there are intersections and entries for parking lots and driveways and such.
These lanes make no sense whatsoever. I can't even imagine the logic behind how they were designed. There's no benefit to being a carpool driving in this lane, because you will always be slowed down by other vehicles turning onto the road or off of it, so there's no incentive to carpool. There's no way to enforce these carpool lanes because anyone stopped by a police officer could just claim that they were going to turn at the next intersection, so ticketing non-carpool drivers is impractical.
I can only assume that this was an idea that sounded good on paper to somebody, but was never reviewed by anyone who had actually driven on a road in their life. I understand the logic behind carpool lanes on the highway (in theory, though they're not particularly effective in practice), but I can't understand these, or why they've continued to exist for more than a year.