I have a question about this highlighted part of an ESL pod transcript:
Mandy: Whoo! Whoo! Theo: Hey, get down from there. You shouldn’t be sticking your head out of the sunroof. Mandy: I just wanted to get some air. This stretch limo is amazing. Theo: Well, I thought I’d rent one and take you to the prom in style.
Mandy: This is the height of luxury. You’ve really outdone yourself. Theo: Thanks, but maybe we should be careful not to spill drinks on the seats. Mandy: Everybody drinks and parties in the back of a limo. Why else would they have a wet bar? Theo: Well, we shouldn’t be drinking out of it. We could get into trouble. Mandy: The chauffeur doesn’t know what we’re doing back here.
Does ** why + else + would has a grammar usage? And what does this question mean? As it is very difficult to understand could you please provide me with some more examples?