Any profit, could be perceived as ''income''.
Anyone who buys and resells at a loss, or for ''cost'', is either temporarily or permanently in an unfortunate set of personal circumstances, or just careless and foolhardy.
As an example, selling on Reverb for a profit is ''income'', selling large quantities on Reverb, lets say a valuable vintage guitar collection for $150,000, which is not unheard of, is capital gain, and taxable.
Here in Canada, selling a second residence is ''capital gains''. Selling expensive collector vehicles is ''capital gains''.
You can be sure the IRS is standing in the wings at Barrett Jackson, when a car rolls across the block for seven figures.
Gambling winnings in Vegas/Atlantic City are taxable. Out of country winners can apply to get the taxes back, but, the the IRS is going to take the taxes first.
I'd have a pretty difficult time, in 2022, convincing Revenue Canada, that the sale of a $500,000. guitar collection, and a million dollar vintage Ferrari, is not taxable income, especially if in 1975 I bought the Ferrari for $35,000., and my ''cost'' for the guitar collection was $75,000.
As opposed to reselling my guitar collection and my vintage Ferrari at cost I'd happily pay the tax. That's still $1,000,000. in the bank, taxes paid, as opposed to $110,000. in the bank, and not having been required to pay any taxes.
As far as sales tax being levied on the receiving end, the receiver is the end, and if this tax is evaded, by whatever means, the receiver (me/you), can be held liable, and made to pay! Which by the way, is the primary reason ''smuggling'' is highly frowned upon. Evasion is evasion.
Just like getting paid under the table sounds like a good idea...GOOD...right up until you get that knock on the door.
You might want to reread my comments. I’ve never said that taxes shouldn’t be paid on profits, but as I pointed out, my transactions on guitars and gear have been a net loss. I’ve always paid my taxes and never minded doing so. Never have I suggested under the counter transactions.
However, having to prove that you are not profiting from a mundane transaction seems a bit burdensome. It’s very unlikely that I would ever make a profit on my guitars. I’m not interested in selling for a profit, but I think that it’s a bit ridiculous to expect someone to prove what they paid for a guitar they’ve owned for decades.