Some cryptocurrencies make it impossible to black hole funds by requiring the recipient to prove they can spend the money they're about to receive before they receive it. Needless to say, these cryptocurrencies do not feature smart contracts.

Afaik bank transactions are also non-reversible. I don't think that is the main issue, although certainly it is a problem.

If it bothers you, you could probably also go through some service that insures your transactions and gives you a degree of reversibility.

I am unaware of any country where this is true. Many countries have limits on how / when transactions can be recovered but AFAIK there is nowhere where bank transfers are absolutely final with no recourse.

In my country (Germany) afaik if you transfer money, the bank is not guaranteed to be able to get it back (if it has already processed it). There are other forms, for example other people can withdraw from your account and you can contest it within a certain time frame.

A service...like...a bank ?!?

Sure, if it is important to you? But I think there are also smart contracts/escrow services that require you to do additional things besides pushing "send".

The classic is for a trade, and the receiver has to confirm they received the stuff before the money is released.

Afaik "traditional" companies like ebay also struggle with that kind of thing.