Users dislike paying on the web because it is a security risk. Because of this insane system of credit cards, where you give the other party a "secret" which enables them to take the money from you.
If you could just send the money, the barrier to pay would be 100x lower.
Most websites pay the bills via ads. And make less than $0.001 per visitor. If they could sell a monthly membership for a one-time payment of $1, they would have a way better business model.