I think what OP meant is that there are reasons for companies to be off-shore which are totally above board.

A common reason that investment funds are in off-shore tax-havens is because they have lots of international investors. If the fund was say in the US all the investors would have to file tax documents in the US even if they weren't US based, by being based in a tax haven it means investors only have to file local tax paperwork and not paperwork in a second country.