I guess since we're all uni students, there's a sense of kinship to help your fellow students, from what I've noticed here. I would do the same in their shoes and I wouldn't even bother them at all had I have my phone with me, so all I could do in return for their help was to inform them about the bus schedule lest they spend hours waiting for a bus that would never come tonight. It's also a good thing that people in Australia, especially Perth, are known for being very hospitable and friendly.