In the United States, there are no national or state level service taxes, so that's a whole branch of businesses that do not have to register for specific taxation purposes.

If the US were a VAT-style country, everyone would have to register for taxation purposes.

Regardless, at least in the USA, sales tax registration is not the same thing as a licence to operate. You can start a business dealing in tangible goods, and begin selling to out-of-state customers without needing to register for sales tax. The in-state registration for sales tax is simply that---registration, there's no qualifications that you need to attain before you get it, and even without registration you are still required to collect sales taxes.

If I understand you correctly, while it's not a license, you must have one to do business and you can be punished for not having one.

So I have to ask exactly how many businesses can you give me the names & addresses of which legally operate in the USA without any sort of government paperwork which they could punish you for operating without?

My understanding is that we were talking about removing the idea of a business as seperate legal entity, not stopping capitalism in general and preventing people from exchanging money for goods or services.

As such, the only 'business' licence of interest is one which would prevent an individual, real, breathing human being from selling goods, or providing services to the general public.

The requirement that you must personally fill out a sales tax form is not that. This is really just on par with the law that says 'if you make an income, you must fill out your income tax forms'. The only penalty for ignoring it is paying additional administrative costs (and perhaps a small punitive fine) because you made everything harder for everyone.

Edit: And importantly, no one can stop you from filling the form so it can't be called a barrier to entry.