I would have no problem if this was true. But it is not. $49 only for non-Face ID Model. $69 for FaceID, or pretty much all current iPhone lineup except iPhone SE. You also have to wait 30 min to hours depending on store. Not few minutes unless you are the only one doing Battery Swap which is highly unlikely given how they are always fully booked.
Depending on which part of the world you are in, your prospective on the Battery swap pricing differ greatly on a $10 Battery part.