Another issue with Venmo is the possibility of shady buyers using stolen credit cards. So a week later, the transaction is reversed and you're out $300 and the item you just sold. As a seller, I'd rather just take cash. The new IRS $600 reporting limit for 2022 is also a joke.
The focus on Venmo is because you are in the US I guess ?
The credit card reversal part is solved by 3D Secure 2.0, where the barrier to get a transaction reversed is way higher (the issuing bank has the responsibility to validate it comes from the customer). I don't know how fast it's adopted outside of the EU, but we're far from the days where you just passed operations with a stolen number and a valid CVC.
You cannot just throw technology at a human problem and expect it to be solved. Scams will always exist as long as there is someone to be scammed. No amount of technology can "solve" this problem.
We're talking here about a case that was introduced by technology (wide possibility to emit chargebacks) and is fixed by technology (severely limit chargeback potential).