Websites absolutely spontaneously send letters, or advertising flyers.
The company could be from china or Russia with little interest in diplomatic pandering for such a small incident.
Providing a user a service in exchange for payment is also aimed at a specific person in a specific country.
heck, if no laws can be applied across borders, it could be a website selling the service of fake extortion letters.
And don't mix up "difficult to enforce" with "legal". Constantly changing domains and hiding who is behind the service are efforts to avoid being caught by very real and enforced laws.