I think all people across the world are familiar with giving or receiving a card for holidays, birthdays or special occasions in general. Crafting the right words to go with some nice visuals is a great way to expressing yourself to someone and many people downright expect it! A well received card could stay around your house for years because of its decorative status and the fact that its nice to read what's inside.
Also have you seen 500 days of summer? It's about an Architecture major turned greetings card creator. That is a big part of why I even started making some of these cards to be honest with you!