You know .com is used EVERYWHERE right?
Companies tend choose it as a suffix to indicate that they operate internationally.
Its original intended purpose for subdomains registered by commercial organizations. Later, the domain opened for general purposes.
But in the early internet pretty much all sites that weren't .org or .gov were .com regardless of if the companies were based in Miami, Tokyo, London, or Madrid.
It wasn't until Google search results started prioritising results that were obviously geographically close to the person searching (circa 2000) that companies that only operate in their own local market started really embracing Country Code suffixes