My mother always believed that having a red door was more than a decorative decision. I researched it and she was absolutely right.
In Feng Shui, a red door is a sign of welcome. In early America, it meant the same thing. You might think that was an odd custom, but it made perfect sense. What if you found yourself traveling by horse and wagon or merely by horse, and having no idea who might take you in for the night. It's raining; it's snowing; you are miserable.
The roads have few signs and chances are, you couldn't read them anyway. And then you spot a red door. You're safe. The door symbolizes welcome. It might not guarantee luxurious lodging. You might even have to share a bed with another traveler, but it's a place to get warm and to get out of the weather.
In Biblical times, Jews were told to smear the blood of a lamb on their front doors to protect their first born from the angel of death. Early Catholics painted their doors red to represent the blood of Christ.
Still want a red door? It's a responsibility, isn't it.