Respect like many things is earned
At various times in school I've had teachers who started off the first class of the semester by saying something like, "As of right now, everyone in this class has an A+. Lets see how many of you can manage to maintain that to the end of the semester".
Of course, very few people did.
Point being, on meeting someone I think we're better off giving them the benefit of a doubt that they're someone worthy of respect unless or until they prove otherwise (and I think most of us do that).
Over and above that there's basic respect for people just based on the fact that they are people, and that they have a few basic rights and boundaries that they're entitled to by default, like; the fact that I'm in front of you in line at the grocery store means you don't get to cut in front of me, even if you're bigger and /or more aggressive than me. etc.