The US has thousands of treaties with other countries, covering everything from human rights to nuclear weapons to tax. The European Union is entirely based on such agreements, as is the United Nations. If such treaties didn't exist, neither would the world as we know it today.
More than 60 of the treaties the US is party to are tax treaties, which are mutual treaties that both countries benefit from. Those other countries enforce those treaties within their borders. That should help you understand what's happening here.
> Not sure where you seem to be confused.
You wrote that laws "need to be enforceable" and then complained about "[resorting] to bully actions". Guess what, that's a big part of how laws are enforced, everywhere in the world. It's why police forces and armies exist. You seem to be looking at individual pieces of the picture without understanding how they connect.