"The catch was that when he went to stake his NFT, they asked for an approval for spending aETH from his wallet. Approvals such as this are normal when interact

"The catch was that when he went to stake his NFT, they asked for an approval for spending aETH from his wallet. Approvals such as this are normal when interacting with smart contracts, since the contract has to be "delegated" responsibility over the tokens in order to move them." - this is a bit surprising - I thought the way to let a contract move tokens was just to send them to it? Approving a contract to move everything from a wallet works like sending everything from the wallet to the contract - it omits the step where you choose the amount that you trust the contract with, why is this the 'normal' way?