Courtesy is a very high form of respect. It honors the divine in all of us. I have had the opportunity to witness some of the most profound courtesy in my life. And I have also witnessed the complete lack thereof. I have noticed that people who forget (or just don't) say "please" and "thank you" tend to take others for granted. They seem to have a very large entitlement complex. It is like they give off the vibe of, "Well of course you poured me a coffee, you moron! That's your frickin' job!"
I tend to stay away from people like that. I don't think they have earned my company just yet. And then there are the ones who just walk into your home without knocking when it is their first time there. Yes, I have had some do that. Just tonight in fact. Long story, but suffice it to say, I learned a lot about the person. If someone has earned that privilege then so be it. But let's face it, first timers have so not earned that yet.
Some think that courtesy is unnecessary. I don't agree. It shows respect and caring and humility. We can show respect to total strangers and we can show respect to our lovers. And so we should show respect equally. Taking people for granted is an ultimate slap in the face for them. And who knows, perhaps that person one day would have been nice to have as an ally instead of someone who no longer cares. We can build bridges with courtesy, or we can burn bridges with disrespect. It really is our personal choice. But either way, we reap what we sow. When we ignore courtesy, we set ourselves up for huge life lessons in humility. And we are the only ones who put ourselves there.