Domains come in two default targeting types:
- globally targeted
- country targeted
Those domains that have a Country Code associated, like .uk or .nz are called ccTLDs (country code Top Level Domains). They are targeted to their respective countries by default and cannot be changed to target the globe. That means it’s more difficult for those sites to appear in searches where the user is searching from or using a different country’s default search engine.
The globally targeted domains are called generic Top Level Domains (gTLD). These include .com and .net and by default are targeted globally, making it more difficult for them to rank in a specific country. They compete in a global market.
For example a .com website set to default will find it more difficult to rank in New Zealand than a .co.nz website with the same content and link profile.
You can change the default targeting for a gTLD via your Google Search Console settings, so if you want your gTLD to compete in the USA domestic market only, then it makes sense to change the targeting parameter to USA.
For websites that use gTLD domains but don’t have targeting set to their home country, but also represent a business genre that is local, like a plumbing service, Google will automatically adjust and ignore the targeting parameter.
The issue with targeting typically only affects websites that represent business verticals who typically (do or could) operate with larger geographic target markets like state, national or global size.