Not everyone is happy to use CREDIT card. You can get a gift card that is top up. Some large shopping centers and shop chains offer them. They will have Visa or Mastercard logo and can be used as regular CC.
It is safer to use a credit card because if you get scammed on a debit card, you can kiss goodbye to your money. If you get scammed on a credit card, it is the lender's responsibility.
Once you get a hold of some online transactions, you will learn how to stay safe. Its not that hard, its just common sense. And the rule applies - if it is too good to be true, it probably is.
Totally understandable and acceptable, but then you can't complain that your CREDIT card isn't being accepted. You can very easily get $500/mo limit credit cards these days. Or indeed, you also have prepaid top up Visa and Mastercards.
Just make sure - if you get a credit card - to pay off the balance in full each month.
Most of the shitty German banks issue a German domestic card with a Maestro cobranding, but don't allow Card-not-present transactions so they can upsell credit cards.
I agree though that not a lot of online shops support payment with Maestro, MasterCard Debit, Visa Debit and to a lesser extend Visa Electron are used a lot more than Maestro.