There are quite a few issues under the surface that prevent thinning in the USA.
A large part of it is legacy views within agencies, budgets that do not allow for the NEPA to even be written (let alone actually do the work) and that's not even counting the people who don't really understand ecological processes enough to understand the need, nor being willing to accept that natural cycles that maintained these systems are not static, not pretty, and that they aren't static.
Lodgepole pine for example....
They need fire to completey burn out old stands in order for regeneration to occur. Clearcutting is the closest approximation of a stand clearing fire, but it looks like hell. Laymen hate it. They sue over it. Yet a lodgepole stand at about 200yrs becomes old and decadent. Without a stand clearing fire, the new cohort cannot develop in the way the species is adapted to regerate.
Our problem is much deeper than most understand.
Throw in encroachment of homes in the interface zones and now we are stopping fires to protect human interests, yet fuels continue to build, systems continue to diverge from functional and humans forget these systems need to have these events to maintain heathy processes.
All in all, "apex community" thought is incorrect and rooted in human values, not natural processes. Trying to force nature to do or look how we want is a large part of our problem, combined with not being able to accept that what we humans consider to be destructive is more akin to doing a clense instead of getting hit by a car. We manage for short term outcomes while it took many many human lifetimes for the homeostasis we perceive to be realized.
TL
R: americans are unwilling to accept the visuals of practices needed to set our lands back on a natural successional path because we want them to stay the same.