You can always use a credit card as a debit card. Pay it off to zero every day. Indeed with the very low limit cards people with bad credit can get, you kind of have to pay it down faster than the bill comes if you want to keep using it.

With cash: you must have the money when you make the purchase.

With card: you can set the cash aside at the time of purchase to pay when the card bill is due.

How does the card give you less flexibility or make it harder to pay for?