It doesn't matter who issues the card. The same practices are used by everyone in the industry.
Bottom line. If you borrow money under the typical revolving credit (credit card) agreement, you are shooting yourself in the foot. There are not many differences in the credit card agreements from one bank to another. What it boils down to is that you have no way of knowing what you'll ultimately pay for something that you charge on a credit card (unless you pay the balance in full every month). Since the card agreements give the bank the right to change anything in the agreement whenever they feel like it (with minimal notice. And no, they don't have to send you a letter), you are at their mercy if you carry a balance. It's like doing business with loan sharks.
Most of this could be avoided if people would take the time to read and understand the revolving credit agreement. Folks like the OP that are surprised that their interest rate could increase, are prime examples of the type of people that do not read their agreements and assume that some bank is going to treat them fairly. Once you read and understand the typically lopsided credit card agreement, you will recognize that borrowing money under such terms is a complete sucker bet.