“Pre-approved applications are common”
maybe RECEIVING the application is pre-approved, but the actual credit is NEVER pre-approved. That’s why they send the application. Pre-approved credit is pretty similar to “you may have won” the National Publishers Clearinghouse Sweepstakes.
Most preapproved applications are actually pretty prescreened: a list from the credit bureau that meet certain criteria, or exceed a certain credit score.
As you note, you don’t actually get credit until they have your permission to get your full credit report.
You can opt out from prescreened credit lists by writing the credit bureaus.