In fact, looey, what that business is doing is STEALING from the government, not "forgetting"
Who said it wasn't paid?....You are really quite dense.
You don't think it's possible for example a plumber (who normally does plumbing not tax collecting and doesn't have a cash register in the van) could forget to include the tax in his bill?
You don't know the difference between collecting and paying I take it.
The plumber would be required to give a receipt to the buyer - and the buyer should insist on one just in case. If the plumber refuses the request for the receipt then he is both violating the law and almost insisting that he be reported.
If the plumber collects the tax and does not send it to the state, that is stealing, looey. Keep in mind the plumber has to be a licensed vendor to collect the tax (for which he is paid to collect and forward - but not pay ... that's the buyer). "Forgetting" is a lame attempt to dodge the requirement he agreed to in his contract with the state.