> The lack of something lighter weight than a full working visa for these sorts of things means the USA is closed for business.
What is “these sorts of things” to you? To me building factories and installing equipment on the factory floor is a different class of work that is generally prohibited under the lighter options like ESTA or a B1 visa. Here is what B1 allows as an example:
Consulting with business associates
Traveling for a scientific, educational, professional or business convention, or a conference on specific dates
Settling an estate
Negotiating a contract
Participating in short-term training
Transiting through the United States: certain persons may transit the United States with a B-1 visa
Deadheading: certain air crewmen may enter the United States as deadhead crew with a B-1 visa