They are indeed usually in inches but that’s probably bleeding back to Europe from the US. And most people don’t actually know how much that would be in metric. It’s sometimes listed but no one I know actually uses those numbers. We just know that 65 is bigger than 55, etc. If we want to know if it fits in our living rooms, then we look at the actual size in cm. I also couldn’t think of anything else that’s imperial, at least here in Germany.