Why is there no failsafe for withdrawals and blind signing contracts within MetaMask or other browser wallets?*

Who said smart contracts need to be signed blindly?

The best practice is to review the smart contract code and make sure there are no gotchas before signing them.

Normies would argue that they’re not capable of carrying out code review, let alone spot gotchas in the code.

But Crypto Maxis would counter that argument by saying that crypto, especially smart contacts, is not meant normies.

Neither side would be wrong.

Not sure what exactly “no failsafe” means but if you’re referring to the irrevocability of the action initiated by the smart contact, well, that’s a feature, not bug, of blockchain’s foundational characteristic of immutability: Once a transaction is written on the blockchain, it cannot be deleted.

If it’s any consolation, even Account-to-Account Real Time Payments in a fiat currency have “no failsafe”. That’s again a feature, not bug, of how digital payments have evolved. Examples of such MOPs include UPI (India), FPS (UK) and Zelle (USA).

As I highlighted in Ketharaman Swaminathan’s answer to How do I revert an online transaction which is done by using UPI ID mistakenly?, by supporting chargeback and revocability, credit card favors the Payor. A2A RTPs emerged as an alternative that leaned towards the Payee by not supporting chargeback and revocability.

As things stand, either a payment method is revocable (e.g. Credit Card) or it is irrevocable (e.g. A2A RTP, Crypto). I don’t know of a third type of MOP that lies in between.

Not saying there can’t be such an MOP going forward but I won’t hold my breath of it emerging in the forseeable future.