I think the expectation is the reverse - a site operating internationally can likely manage to set up additional domains. It needn't be particularly tricky or expensive, and can be heavily based on your existing site. But if they're overly similar, you'd essentially be creating sites that all compete for the same rankings.
Part of the problem with subdirectories, is that it's by no means a certainty that those country codes are actually country codes. "Es", for instance, is also an acronym and many other things. You can find quite a few examples with advanced searches:
Add to that fact That Google language detection is far from 100% (English pages? [google.com...] ) and you can see that you'd be chancing it with country codes in a directory name.
In comparison, and local TLD is an absolutely explicit declaration of intended geographic target. You'll immediately end up with listings in local search engines and localised results from the major search engines.
For Google there is the "set geographic target" option, I suppose, but that would be a severe compromise, at best.