Because there's a large capital (and learning curve) upstart requirement. It's almost like you missed this: "(once you start developing the resource)"

Additionally, tar sands are very marginal economically. Arguably not profitable right now. Fracking tight oil is cheaper, and even that is not being pursued as vigorously as it was when oil prices were higher.

And there are environmental regulations that get in the way of oil shale/kerogen extraction. And for good reason.

That was true too for Oil Sands and Tight Oil. (Heck, any oil play needs capex, starting from the first drilled ones!) And yet we are... P.S.: But we basically seem to agree, so this is nitpicking on my part...