Someone had to build a giant platform in the ocean, drill a hole deep into the ground, pump the oil out of the ground and move it ashore, boil it in a giant distiller to extract the gasoline, pump it into a tanker and drive it to your gas station. All of that stuff is invisible, but you notice the gram of polythene wrapping on a cucumber.
A phone is an incredibly sophisticated device, but it's only a few ounces of stuff. It cost you $700, so it feels like it should involve a huge amount of natural resources to make. It required a lot of human skill and ingenuity, but we didn't need to burn a lot of stuff to make it. When you fill up your tank with $50 of unleaded, you don't think about the huge volume of pure hydrocarbons you're pouring into your car or the immensely energy-intensive processes needed to extract, refine and transport that fuel.
When you get on a plane, you don't think about the fact that almost the entire volume of the wings are filled with fuel that'll be burned in a single journey. When your heating thermostat clicks on, you don't think about the volume of gas rushing through a network of pipes to feed your boiler.
I mean, building a smartphone involves digging for raw materials, extract them, transport them, assemble them, etc. And i'm not counting the emission during the design process.
I know that a two-hour car journey is really not optimized, and that manufacturing phones on a large scale is very optimized, but it seems impossible to me that manufacturing a phone in China from components from all over the world emits less that a good big steak in a restaurant... I that's true, that's incredible.