> If a company in California has ample opportunities to sell in Florida (>2000 miles away), why then is it significantly more difficult for a company in Greece to sell in Denmark, which is a much shorter distance.
The US has a federal "interstate commerce clause" which means that individual states cannot regulate trade with other states. The federal government has all the control, which would be like the European Union having control.
https://en.wikipedia.org/wiki/Commerce_Clause
