You're joking right? - Cars see far more abuse. They spend all their time outside in all weather conditions, they have 1000x more parts, at-least 100 moving parts if not more. They get driven in potholes, get fender benders all the time.
All this phone has to do is move a piece of plastic up and then down again. I've seen lego actuators do the same thing more than 500,000 times at brickworld events and still they keep working, even when the plastic is wearing away from bricks rubbing together they still work.
LEGO actuators have been immersed in alcohol, salt water, chlorine water, toilet water, greasy foods, some bodily fluids, etc. If it has I don’t want to know details
Cars have been around for a century and are built for to withstand normal outdoor environments. Not much has changed. Compare that to a phone with a pop-up camera in all sorts of situations. I know one person who downgraded to a non-smart phone candy bar form as all his phones have suffered an ill fate and he had an otter box on those phones. Colour me surprised however there are some people who break everything.
What happens if dirt gets onto or in between the mechanism or some fluid, I can just imagine people forcing it to close or it stays ajar and who knows what else.