Of course you could ask the buyer to transfer the money and wait for it to clear before handing over the keys, but that just moves the uncomfortable and stressful situation to the other party (I wouldn’t want to transfer someone money and then have to wait a few days for it to clear before they handed me the keys) and doesn’t actually solve the underlying issue.
Giving the account owners enough time to contact the bank if the payment is unauthorised, but when the waiting period is up you can then choose to release the funds at a time that suits you (eg. for a car sale, when you hand over the keys) or you can choose to can the transaction returning the funds to your account.
Wishful thinking I know, given how much of a mess the instant payment system is at the moment. I had an account that supported PayID with Macquarie and tried to transfer money to another PayID account with Up bank and found that because one of the banks (Macquarie iirc) didn’t support whatever underlying payment system Up used (Osko possibly) I wasn’t able to use PayID and had to use regular EFT instead.
I sold a car through gumtree here in Aus a few years ago, the buyer sent a bank transfer, I received it, went about my day. Seems very similar to the UK (where I have spent most of my life and still have accounts/make transfers).