I'm a little surprised they replied. Also yes they may sell $1 hotdogs, but if a customer comes in to purchase a $1 hotdog, they are unlikely to be leaving their car parked there for long, plus the all important thing is that the person purchasing the $1 hotdog I would image they would actually need to step foot into the ikea store to make said purchase? Not sure, never seen hotdogs at our local ikea, don't know if that's an instore thing or a outside like bunnings thing.
In any case it a person whom is within the generial Ikea area and could be swayed into purchasing something more unlike a person whom has flown off for a week and is therefore going to be making exactly zero purchases in that time, but taking up a car space from a person whom may come in.
(Comments about the car park been almost always empty are moot, if they offered it to one, there would be others whom would ask for it as well)