It’s chargeable at Tide, so I would expect Starling to charge for it really.
It’s not a basic feature everyone would need, so it makes sense to charge for it.
It would also be consistent with Starling’s overall strategy, of making additional services chargeable to cross-subsidise keeping basic services free, to charge for this.
Expense cards would be very easy for Starling to implement. They already have the tech ready to go with the Kite card. All it would need is a different name adding as the functionality could stay the same.