I written my share of government documents and standards and understand document and legal structure quite well. Chapter 5 is titled `CHAPTER 5--OTHER ADMINISTRATIVE PROVISIONS". Section 509 is its own stand alone section. It is not a subsection of another section, but stands alone. There is no 'context'. There is nothing in Chapter 5 that says these provisions only apply to business who are required to collect and remit. I would bet you $100,000 if you really think otherwise.
Could have fooled me. In order for the provisions of this section to be invoked, there has to be some grounds for a dispute. The only way there can be a dispute is if the entity is liable for oversight in the first place. The only entities liable for oversight are those required to file reports -- retail sellers and certain special cases. Not everyday people buying retail goods and services.