The fact that LLCs exist would not be sufficient if they are used primarily for tax avoidance.
Further, LLCs are strictly creatures of state law. The IRS does not even recognize them as a separate type of entity as they do other entities. Rather, the IRS treats LLCs as disregarded (sole proprietorships if they have one member), partnerships (if there is more than one member), or corporations (if the member or members make an election).
