Soldato
To be fair, the old banks are copying this now. HSBC now does Starling/Monzo-like notifications although they don't have the spending data that is interesting too (I kept my old account when I switched). The old banks still have the legacy technology problem though and won't be up to Starling / Monzo levels unless they replace their whole technology stack.
they have had 5 years to update their tech. They could have developed a whole new stack and had it run side by side with the old one until they were sure it's ready.