What if you want to change processors? If you weren't storing the CC details, wouldn't you have to have customers enter all their details again? I imagine this could cause a drop in revenues due to people either forgetting, procrastinating, or just not bothering.

It's never cool to be actually- or quasi-locked into a vendor.

Most decent processors have processes in place for the transfer of CC numbers. I was involved with this process at a decent-sized magazine, it involved armed security, an encrypted hard drive in a locked container and millions of dollars of insurance. It's not an easy process, but is possible.

Sounds ... expensive.

Some will let you export the data, but it's a hassle. They burn it to a DVD and ship it to you and you have to sign tons of stuff freeing them of any liability.

Otherwise you just ask customers to re-authenticate. Often you have a few months headway for a switch like that.

Said processors allow you to export credit card data to another processor without having to store it yourself.

It seems there are a LOT of incompetents then. Are the payment processors you're talking about something the vendor interfaces with in the background and not a third party that is directly utilized by the customer (eg. Stripe, Paypal)?