Only when it's the literal only option at checkout. Then it's the merchant's choice, not my problem. When possible, I'll always opt to use a different instantaneous method (e.g. iDeal or direct debit), or give the merchant my money directly and wait 3 days for the IBAN transfer to go through. Using paypal just risks the money being indefinitely frozen on either side and them taking a cut for the privilege, if it works on a particular day in the first place (no mysterious errors or infinite loading screens)
As for "the real world", there's cash and chip+PIN. Never used paypal IRL. Is that a thing in your country, did you mean that literally? If so, where are you from?
If the merchant screws you on a transaction paid via IBAN transfer, how do you get your money back?
Same as if Paypal screws me, or the store I just bought something in... you talk to them and if they don't cooperate you take it to court (small claims hopefully). So far, nobody I know has needed to take a shop to court. It's extremely rare, but yes it sure happens
If I really don't trust the seller, I can always still get some sort of insurance thing, but an X% insurance fee needn't be the default for every transaction. (Even if the % is invisible to you, then the seller updates their product's prices. The seller won't choose to eat less just to finance your transaction fees... the only way to not pay those is operate a deficit, which eventually leads to bankruptcy and loss of your warranty, which isn't a desirable situation either)