Common to get a big discount on the first purchase. That way it looks something like “just take 5 minutes to sign up here and you’ll get $30 off your purchase today”. I feel bad for the staff that have to push it, which gets me frustrated because I just want to buy my things and go, so I end up being rude to them.
I think part of the solution is to add some regulation that say that you should be able to close the account in the same way you open it. Let me sign up, get the $30 discount, pay the bill, close the account, and have them delete my personal information so I can do it over again next time. Few people doing that and it won’t be worth the effort for business to process everything.
Sure, the occasional customer gets into a cycle for credit card debt and ends up paying big interest. That’s not where credit card companies make their money though. There’s a fee for the merchant to process each transaction, that’s the main revenue source. Then if we’re talking about a store card, they get the ability to track your purchases everywhere you use that card, and use that info to do better marketing, merchandising, and just generally get better at selling people stuff. It’s nice to make a buck when people buy things from your store, but it’s even nicer if you can make a buck when people shop elsewhere too.