U.S. business laws are Federal in scope and vary from state to state. P.C. Please read the attached disclaimer. Why not consult with one before starting a business that could seriously affect their immigration status and their lives. Sometimes, it is lack of understanding of the immigration attorney's capacity to advise them, but in most instances it is lack of initiative. Planning ahead is very important in realizing the goals of your business.
Nobody can plan for all that can possibly happen, but one can definitely plan for the worst.
It sometimes depends on the nature of the business. The principal advantage is the protection that a corporate form of business offers to the individual is protection of the investor's personal assets from attachment to satisfy the debts of the business. In other words, 'Limited Liability'. However, corporations require enormous amount of maintenance in terms of paperwork, mandatory taxes, etc. Most corporations in the United States are closely held corporations.