San Francisco voters passed Proposition K, mandating a BRT line on the heavily-used Geary corridor in 2003. Yes, 2003!

It's 2021 and the furthest they've gotten is upgrading some signals and painting some side lanes. They haven't even begun construction of the dedicated inner lanes, which won't even run the full length of the corridor, anyhow. In fact, last I heard there are plans to scale things back even further.

Our inability to build transit isn't an engineering problem. It's not even really a capital expense problem, though don't underestimate the expense of building out dedicated lanes at-grade. It's a political and governance problem.

Last time I looked at the project details, IIRC about half of the $60 million budget was simply going toward repaving Geary Blvd, a benefit inuring almost entirely to cars. (They've postponed repavement so it could be rolled into, and hidden, by the BRT project budget.) If the BRT-specific changes were left out, the project would have been approved, finalized, contracted out, built, and finished a decade ago. The only reason it's taken so long is because of all the infighting that occurs for any infrastructure project beyond building roads.