As per your linked article, they mainly either give away their money to charity, or they set up trusts. When beneficiaries receive money from the trust, it's taxed as income.
You could also just... not pay. And then lawyer-up when the IRS comes after you. (They will not come after you, because they know you've lawyered-up and aren't going to make it easy.)
IIRC this is part of how they avoid taxes in general. Penalties don't hurt enough for the ones who do eventually face them.
You missed this part in the article: “ Estate tax planning has become so effective that wealthy families can now easily pass large portions of their estates to their heirs without paying the tax”
The beneficiaries then set up their own tax avoidance schemes. With the effect only rich people with poor tax planning skills, to quote Gary Cohn again, end up pay the estate tax.
IIRC this is part of how they avoid taxes in general. Penalties don't hurt enough for the ones who do eventually face them.