It has always been prepaid. Not one single provider or exchange offers a card with a credit line attached to it. Earlier cards offered by Cryptopay, Wirex, Advcash etc all required coins first be converted to fiat. The money (USD, GBP, EUR) was then loaded into the cards. The cards worked only after completing the loading process. So essentially one had to prepay funds into the cards before ATM and merchants honored them.

I'm sure fraud was not the only concern behind the Wave Crest saga. It probably was triggered by compliance issues. Accepting KYC documents from less developed economies is a very challenging process. Unlike the US SSN system and the EEA's national ID card system, it is difficult to verify and authenticate an ID from, for example, Brazil or Vietnam or China and all those other countries.

And another cause of the Wave Crest card drama was that one unknown factor. Where was all that money loaded into the cards coming from? Were they laundered funds? Looking back, I think I can understand Visa's decision to shut down the Wave Crest card program. The card had a daily transaction limit of USD 2000 with no lifetime and annual limits, making it a convenient tool for money laundering. One only needed 5 cards to hit the 10k USD transaction limit, a reportable threshold. But of course none is ever reported.