I went to the gym today. I go almost every day, except that about eight months ago I took a day off and didn't go back. It seemed mostly familiar - with the caveat that since it was July 4th, there really weren't that many people working out. There was someone there I haven't seen before, straining with 275 pounds on the incline leg press. When he'd finished he got up and staggered away and did some back exercise. I assumed that when his legs had forgiven him, he'd be back to take the plates off the incline leg press machine.
He left the plates on the bar after his next exercise too. Tubby white dude, probably 225 pounds, most of it in his beer gut, long kinky hair. Pretty old too, about 45. I'm talking about you. Yeah, you! You left your weights on the machine for the next person to deal with, you asshat! Perhaps you can't lift 45 pound plates and had to leave them on. Maybe that's why you were struggling to rep with such a girly weight on the machine. In which case I (mostly) forgive you.
It's up to the person who loads the machine to leave it ready for the next person - it's the rule at that gym as well as polite. I lost a lot of upper body strength after an operation a couple of years ago and I don't like lugging them around myself. Every time someone leaves a bunch of weights on a back or leg machine, or bar, it can cost me the opportunity to use it.