As someone who's worked on industrial machinery for food production all my life, I'm consistently amazed at what a simple dishwasher can do, and how it can do so for YEARS with essentially zero maintenance. Cleaning food residue is HARD.
I just bought a new one recently (the old one wasn't actually broken, despite being very old, so I gave it away), and I can't help but open it up every once in a while to admire it. How much time these devices save us!