PayPal is at present the best way to guarantee that neither the buyer nor the seller is cheated or scammed. A seller doesn’t get his money until the buyer has received his goods and is genuinely satisfied that he’s gotten what he was promised.
It doesn't work that way, never has. What you are describing is an escrow service, which PayPal is not. As soon as the money is in your PayPal account you have access to it even before you ship. You can use it to buy other things or transfer it out to your bank.
The buyer can come back and file a claim if not satisfied and PayPal can take the money back, but PayPal does not hold it until the buyer states they are satisfied.