Protection is territorial. A US registration does you no good in a market where somebody else registered first, and in first-to-file countries the person who registered first generally wins even if you used it first.
The Madrid Protocol lets you file one international trademark application and designate member countries from it. The PCT does something similar for patents, buying up to thirty months before you have to commit to national filings.
That delay is the point. It moves the expensive decision to a moment when you know which markets actually matter, rather than guessing at launch.
