This is not my understanding of how the tax code works. If the garage sale is not part of a business and you are selling an item you used for less than you paid for it, you generally have no reportable income. Everything I could find online seems to agree, [1] for example.
Agreed. I think the parent is confusing it with the case where you buy an item for your business, depreciate it to zero (thus deducting its full value as an expense), and then later find out you can salvage some value on resale. In that case, you would have reportable/taxable income from that resale, which you can think of as “correcting the overdeduction for depreciation.”
The link you posted explains the difference between business income and hobby income. It just depends on how often you have a garage sale. Like everything with the IRS, it's complicated, and also they usually don't care with small amounts anyway.
Do you have any sources?
1. https://www.findlaw.com/tax/federal-taxes/do-you-need-to-rep...