My debit card has a $5k a day spending limit, and a $1k a day cash withdrawal limit. Why have a lower cash limit?
If I make a transaction with a merchant with my card, it sits pending and then "settles", at which point the merchant has access to the funds. Once a transaction settles, the bank can no longer claw it back; Meaning, from their perspective, if the transaction was fraudulent either them, or the user looses money. Settlement time is why it takes a while for card payments to show up in your bank account.
For this class of transaction, the bank takes on limited risk. Slow settlement times and the ability to cancel mean, if a transaction appears bad, banks can claw back their losses (passing the cost to merchants). During the settlement period, banks are immune to fraud if they can catch it. Thus, banks have strong incentives to invest in monitoring and fraud detection systems.
Clawing back a fradulent ATM withdrawal is more complex and likely involves local police. My debit card suggests its about five times as complex. Hence, the unreasonable effectiveness of Slow Finality.