As a consumer, I like additional options. So I think it would be great if Upwork would accept pre-paid cards for payment.
But they don't.
I don't think they will any time soon.
And I don't blame them. It just doesn't seem worth it to them. Because basically clients want to hire freelancers, and freelancers want to log time while working on the client's project. Upwork wants to know that the time will be paid for from the client's credit card or PayPal account. Upwork just can't rely on the pre-paid cards for this enough to make it worth their time.
With pre-paid cards, they would be burned too many times. They know that too many times they would be dealing with scammers or people who can't really afford to hire freelancers. (Not you, of course, but other people.)
So Upwork disallows pre-paid cards, knowing they make more money this way.
That's sad. I am a freelancer on Upwork myself and I have positive balance. I live in Ukraine and almost no one has credit cards here, only debit. So, I cannot pay with Payoneer, nor with ukrainian card.... and even not with my balance.
So, how can I hire another freelancer?
You can make no real money, you can use "Points", which possible to buy and convert to the real money after or spend on payment of free-lance services with some fee.
or organize a possibility to start a work with free-lance with a prepayment via your side, which you can hold as a guarantee until project will be finished, this scheme realized on the website of your competitor - **Edited for Community Guidelines**
In other cases, you will not have a lot of customers from Russia and Ukraine. Because for our countries not possible to have real credit cards, like in US.