[toast0]

Yes, but also no. The US has a basic fluidity of business. You can build things at home (in your garage, if you have one) and try to sell them and establish a formal business later, if the business justifies the process. For a one person business, there's not really a lot of requirements to formalize a sole proprietor business either: often a local business license (which is mostly guaranteed issue and just a tax collection point), a 'doing business as' filing if not using the person's name, and obtaining a tax id if needed (the IRS will issue one online in minutes, as I understand it), hiring people comes with more requirements.

Being able to start small and informally allows many more businesses to start.

[dukeyukey]

Worth pointing out the same is true in other countries - in the UK, a sole trader business doesn't need to notify the government they exist at all until tax return time.