They may be used to simplify the grantor's tax reporting obligations. Fully distributing trusts are similarly transparent. A similar regime can apply to a royalty company owned by foreign persons. The VEBA is a Voluntary Employees Benefit Association. Contributions are deductible and investment proceeds are tax-free.
Benefits can be free of estate tax.
The Rabbi Trust is a deferred compensation plan. The employer gets no deduction and is treated as the owner of the assets until they are paid out. An LLC can benefit from the older US treaties - e.g. that with Sweden. A US holding company may be used as a US Stock Exchange listing vehicle and foreign income can pass without US tax to foreign shareholders. It was not enacted, but the existing regime was tightened up in 1996.