Hussein Nishah once said, "Respect is earned, not given," and people have been parroting this phrase ever since. Many applaud and embrace this quote but I find it deeply problematic.
The implication here seems to be that our default setting with everyone we meet is not respecting them. And it is only after they have proved their worthiness to us in some way that we respect them. What feat must someone perform to earn our respect? It is unclear. But I worry about the time between when you meet someone and when they have finally earned your respect and how you are treating them in this interval.
Let's say you're checking out at the grocery store. You don't know this cashier and they have done nothing for you except scan your groceries. Under the philosophy of this popular quote you don't owe the cashier respect because they haven't earned it. If we follow the "respect is earned, not given" idea we will end up treating every stranger we meet like garbage.
I propose a new mantra to replace the flawed one we have discussed: "Everyone deserves respect unless they have proved that they don't." Our default setting should be to respect every person we meet. Every single one. If you have zero information on a person, you should still respect them because they are a human and deserve human dignity.
To go back to the cashier from before, you may not know them but you can recognize that you're a person, and they're a person and you owe them the same respect that you would hope they would treat you with. And even if they may not be the friendliest, maybe they don't tell you to have a nice day, I would still encourage you to wish them a nice day.
To address the second half of our new mantra, I am in no way suggesting that you must respect everyone continuously regardless of their actions. If after getting to know a person you realize they are very cruel or bigoted, or they have demonstrated a lack of respect and understanding towards their fellow humans, you don't have to respect them.
However the great majority of people are not horrible people, so we should go ahead and assume people have some good in them and respect them. We are all part of one big community of humans, so treating every single person respectfully is a safe bet.
I will leave you with one final piece of advice. My mom always told me growing up "treat everyone you meet like it's their birthday because you never know it might be."