A couple of things to point out.
1. Sales tax is technically collected from the buyer, so the sellers aren’t directly bearing any sales tax cost…there is of course an indirect cost of dealing with the administrative burden of collecting and reporting said tax.
2. 1099 reporting has always been used to report gross sales, not net profit. The threshold for reporting sales of goods has now been lowered to the same level as sales of services has been for years.
3. 1099 reported income is generally reported as sales on Schedule C of form 1040, then you deduct all of your expenses and cost of goods sold…obviously, you’ll need to have documentation support for the expenses if you get audited. If you have net income, then you’ll owe tax, if you don’t have net income (in other words, you have a net loss), then you won’t pay any tax. This has nothing to do with itemized or standard deductions.