Sure, anyone can use any name, but should they? For instance there have to be some limitations on calling yourself General Hospital unless you actually have a medical license.
It's intentional that trademark registration is reasonably easy, but enforcement is more thorough. When (say) 99% of trademarks are not contested, this saves the government agencies substantial resources.
Think of it like a software optimisation where edge servers cache files when they are requested for the first time, but not proactively when 99% of files are not requested.