Historically, it has been. That is set to change in 2022, as a part of the stimulus bill specified that payment processors (like PayPal) now must issue 1099s after only a handful of transactions (versus 200 in the past) and/or $600 (versus $20,000 in the past).
Technically, you were always supposed to be paying taxes on these things whether you were issued a 1099 or not... the new legislation just makes it more likely that people will pay the taxes since they will be much more likely to be issues a 1099 tax form.
well the IRS considers online “yard sales” to be tax free if you’re selling used household goods that you paid for and used. Collectibles get hammered - not sure how they consider other items