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.