The root issue is probably moral
(about business and societal ethics) as much as it is simply technically legal. Do we want
a worldwide jungle economy, do most of us want people like Bernie Madoff, Conrad Black or typical banana republic oligarchs to run things the way they'd like to? Corporations and companies don't exist in isolation from society, many of them need an effective, reliable judicial system, trained people they can recruit and good communcations to be able to operate properly. If established corporations or even financial firms are constantly whisking off their transaction to tax havens to achieve minimal taxes or no tax at all, and if companies are regularly getting drained on money and assets by financial scammers, then much of the economy in a country is bogged down in the end.
Tax havens do create opportunities for financial and corporate fraudsters, for companies whose business idea is to scam people almost with impunity (because it can cost a fortune to attempt to bring a bogus company to justice, and most people, even small companies, don't have those financial muscles) and for people who deal in human trafficking, the financing of terrorism, smuggling and so on. Even if the preparatory business maneuvers themselves might not be illegal they are often closely linked to those kinds of criminal enterprises, and that's where the big money enters. Only this afternoon I heard about one guy here from Sweden who had been spotted in the Panama papers; he has long been known to have been involved in one of the biggest and most infamous financial scams in Swedish history, the so-called Trustor affair
about two decades ago. Essentially he and some business associates in Sweden and the UK (including one Lord Moyne, member of the Guinness family) set up an operation where the financial holdings company was bought by these outsiders with covert use of its own money to pay for the takeover, equal to about a hundred million bucks at the time (this was achieved by some quick to-and-fro'ing between various accounts in various banks, making it look as if Moyne personally had the money). After the deal had gone through, much of that capital disappeared, most likely to various tax havens, anonymized companies and secret bank accounts abroad. Most of the key people involved in this scenario were never convicted, many of them pleaded that they had not understood anything to be strange about what they were "being asked to do" or had no criminal intent, and some of the courts went with that.
Anyway, today the newspapers are reporting that one guy in that affair who actually had been convicted (though with a relatively brief sentence) had been in touch with these Panamanian guys a few months before the scam went ahead, asking them if they could help him "take care of" dozens of millions of pounds. They had accepted, but eventually they dropped him as a customer, saying he seemed to be a liability. That was most likely because by then the scandal had erupted in the news media in Sweden and in the UK. So they didn't hide the money siphoned off, but most likely other companies managing these letterbox companies, and other tax havens, helped out with the same purpose. It's known that some of the Trustor money siphoned off by our man landed in Liechtenstein, a stamp-sized country in the Alps that's also a famous tax haven.
If the basic idea is that a company should
pay a big part of its taxes where its work is actually performed and where it has employees and makes its profits, then siphoning off all the funds to places like the Cayman islands, Anguilla or Monaco seems seriously unethical and destructive, even if it's not illegal. Of course that's not how most billionaires would put it, but so what...
When it comes to why this isn't getting discussed more loudly in the political arena, could it have something to do with big companies and their lobbyists having been able to tilt the playing-field and some of the tax and corporate legislation to their advantage? Some big corporations today have more funds, more revenue and more legal experts than many mid-sized countries - and far less obligations than a state would have. They're definitely able to wrestle down some states and their politicians, taxmen, courts and so on.