They seem to be trying to figure out options. Bus, metro, taxi, uber type thing. If the other option is $15 and the gas at 25mpg is $17 I’d say thanks so much and choose paying gas. If it’s $15 vs $40 and my budget is tight I’d say thanks for the offer, but I can’t really afford that. While it might seem rude up front, it’s better than accepting and then backing out because of cost.