It’ the reason there is no sales tax now.
No it isnt. It varies by state.
Citing the constitution and pretending it applies to state law is shady st best. Context is everything. For example claiming free speech rights when the government has done nothing to make such speech illegal is nutso. You can say whatever you want. If it offends a private entity they may act to remove you (in a restaurant for example).
The Constitution is primarily for defining and limiting the federal government