I'm not familiar with European prepaid debit cards, but they sound similar to what in the USA we call "gift cards": the latter are "preloaded" with a certain dollar amount which the holder of the card can spend in transactions using the gift card, and they are practically never "refilled".
If the above describes the prepaid debit card you are referring to, putting myself in eg Google's shoes re your (heavily paraphrased) question:
> why don't certain "global" companies like Google not accept payment for some of their services via prepaid debit?
I'm in business providing a long-term open ended service (cell, ISP, household utility). I want to ensure ongoing receipt of monthly payments for the service I am delivering with minimum hassle to myself and my customer. If I accepted autopay from a prepaid debit card (as I define it above), the card is certain to "run dry" at some point, guaranteeing a need for future intervention in the payment setup, and (unless the consumer is closely monitoring the prepaid card's balance as the months pass, which is unlikely) likely an interruption in the stream of monthly payments, with an associated likelihood of me interrupting service to the customer due to lack of payment (all costing me administrative overhead), resulting in me possibly losing the customer's business for good.
With autopay tied to a bank account, the primary payment risk is insufficient account balance; with autopay tied to a credit card, the risk of insufficient balance is nearly nonexistent; in general, the risk of interruption of payments from these two payment sources is low (vs nearly certain with a prepaid debit card).