Earlier quoted context omitted.
Go run a local retail business in conflict with state law and regulations. Then tell me how irrelevant those laws are.
The law only says by whom and how the tax is collect, it doesn't specify the tax burden, because it can't, that's only observable and happens due to supply and demand.
Whether you believe the above or not - and I’m not going to discuss that part further, because this is all easy to find online - the fact remains that most sales taxes must be charged separately from the product price at checkout. There are, as I said, exceptions for bulk goods.