Unless the cars are perfectly washed and clayed, even running a clean finger over a car is likely to introduce scratches. I just wouldn’t ever touch someone’s car.

You can look up people even trying to detail their cars to make them cleaner and end up leaving “love marks.” It doesn’t matter how soft the thing you’re using is. It’s because the car has contaminants on it and by rubbing anything on the car, those contaminants end up scratching everything. It’s like when you’re at the beach and you’re trying to remove sand off your skin. You’re probably not aggressively rubbing it off or using much pressure but it still hurts. It’s the same with cars, it’s just that the rocks aren’t as visible to you. They will leave swirls and scratches though… which become noticeable.

I’ve had people just lean against my car when it wasn’t completely clean and completely ruin the paint requiring an entire 5 stage detail.

Cars spend a significant amount of time outside and they depreciate so quickly it just doesn't matter. One shouldn't expect a paint to stay perfect the same way we expect our skin to wear and age over the years.

I don't even know what a 5 stage detail means but I can safely say you are overreacting. A car is just a tool and a rando putting a fridge magnet or leaning against your car once in a while is just completely negligible compared to the amount of shit a paint is exposed to when driving it. Sand and dirt do not ask for your permission either.

> I’ve had people just lean against my car when it wasn’t completely clean and completely ruin the paint requiring an entire 5 stage detail

Assuming this is true, it seems like something has gone badly wrong somewhere in this process.

Why can't cars have paint that survives being "leaned on"

If we're taking it this far then driving on the highway is like sandblasting the paint with dust and you do that without even thinking about it.