Does my reflective vest make me invisible?

I started a new job to 1 have something to do while I go to school, 2 make some extra money, and 3 not have a gap in employment history. Well part of this job is to round up the stray shopping carts from the parking lot. OK not all of them are stray, some are put in the proper place but you get the point. They send me out wearing a reflective vest, I don't know if this is so people will see me or know that I work there, either way it doesn't help. Just the other day it was over 100 degrees outside so needless to say I was miserable. While trying to push around 15 carts at once, this may not sound like many but it is a heck of a workout especially going up hill, cars and people would look right at me and race to get in front of me. Anyone have any idea about momentum and how once you stop it these carts takes a lot of energy to get started again? To do this for hours at a time, sweat pouring off me, about to get heat stroke, and you run a stop sign so you can miss me by inches only because I threw my body into the carts to stop them from hitting your car. What the hell, was your air conditioning annoying you? I'm sorry I was doing my job and making sure you have a cart at the door (which most of those same people would complain to a manager about if there wasn't a cart). Is that gallon of milk going to run away if you just wait 10 more seconds? Sorry for the rant I just had to get that out of my system.