DavecUK, internal heating elements are nearly 100% efficient. Induction heaters are around 84% for stoves. Maybe a little higher for an espresso machine. I will also assume that the exterior of the tank is the induction element. This would make the machine also have higher standby losses (higher delta T).
Maybe it is about speed of heating? The surface area of the induction element might be bigger. It would be interesting to see the volume size of the boiler in relation to the wattage of the heater.
Or maybe it is hysteresis?
I’m just guessing plausible reasons. Very curious to the reasons. It’s likely more expensive, so wouldn’t do it without a good reason.