I've never used them. I just use my regular credit cards and pay the bills on time.
Not sure why people would use them unless they bought them as gift cards to give to somebody else. Seems like it would be a pain keeping track of the running balance however.
The prepaid cards might have value for online purchasing and travel.
At $5/month they tend to be too expensive for regular use by me.
I use a debit card and wait for my checking account balance to go well below $1000 below buying online.
Some people have lousy credit histories. They can't get credit cards, yet many places won't accept cash or checks (e.g. online shopping). So they use cash cards.
Santander blocked my card under the premise that they thought a $80 (approx.) purchase of bike tires from Texas was suspicious, which is the 3rd time they did it. The second was due to the donation to a Christian ministry. They require me to show up at the bank and show valid ID, which I no longer have (did not renew license in time) and would have to pay about $50 to obtain a certified copy of my birth certificate, go to the registry etc.
But the bank accepts SS retirement, and still lets me transfer funds to PayPal, which provides a Master card debit card which Comcast, Amazon etc, accepts, thank God.
At age 70 I think I may live out my remaining years with no valid ID. Or course, PayPal is sailing to port as well so we will see how far their censorship goes.
I gave them as gifts from my bank but none available in this area at bank or in stores.