If I wire 200k I honestly don't care if it takes a few hours (nowadays, old-school SEPA transfers don't necessarily take more) and happens only during business days/hours. It gives everyone more room to cancel if you fucked up.
It's mostly useless I think because when you close on a house your notary is doing an escrow service, and I paid my house by bank transfert to my own notary (couldn't do it online, and their weird bank doesn't support receiving instant transferts).
No fucking way I’m gonna leave some random with both the car and my 200k. So instead of sending a bank transfer, I still have to show up with a big bag of cash in 2022.
The amounts where multi-hour transaction times are consistently acceptable will be significantly higher, 200k is still well within normal everyday p2p transactions.
You should probably get out of your bubble.
That said, it's a false dichotomy. You can perfectly allow sky-high limits to SCT Inst for customers who regularly need it, yet have more reasonable policies for the 99% of the population who's perfectly OK with a slow transfer when they wire money to a notary public to buy a property.
This leaves the seller with both your money and your car.
The current way banks process non-instant SEPA transfers is very predictable and not a problem in some scenarios. SEPA is huge and breaking the old scheme to force everyone to move to SCT inst doesn't seem realistic anyway.
Similarly, the UK hasn't stopped using BACS even though the availability of Faster Payments is ubiquitous today.