Switch / Meastro Debit is being dismantled
As I recall the UK banks handed over the running of the Switch debit card scheme to Mastercard a few years back, Mastercard rebranded it Maestro.
The banks/mastercard don't make much out of Maestro debit , it's a fixed fee to the retailer (30 odd pence - total 30p) and thats it. It incurs no % of the transaction charge, unlike the competing credit card schemes (30 odd pence plus 2.2% or so of the transaction value, so on a £100 transaction that totals a charge of around £2.50).
Since getting hold of it, Mastercard/Banks seems to have buggered around with the scheme to make using Maestro Debit inconvenient for both cardholders and merchants, IMO because it's not as profitable and competes with the more lucrative credit card business.
I don't know why Google have declined to be upfront, and simply state why they are dropping such an important debit card scheme? Perhaps it is to do with 3D Secure (Securecode, Verified by Visa), but the 3D system is already deliberately used to distort and limit competition within the online payments market.
There really does need to be an OFT investigation into the continued undermining of the less profitable debit card schemes. These debit card schemes should be properly protected, we shouldn't be pushed towards indirectly paying £2.50 to the card schemes/banks just to purchase £100 of goods online, just because the debit card schemes have been made delibrately difficult and unattractive to use.