Because they are not remotely safe. Their answer to detected fraud is to freeze the card and keep the balance! Yes - you read that right! They stop thieves from getting your money by keeping it for themselves. So the net effect is the same to you the paying customer.

Avoid them at all costs.

They use diffusion of responsibility by partnering with other entities like Flagship to confuse the customer from understanding which aspect of the scam is conducted by which entity involved in particular aspects of the crime.