As a veteran racer, volunteer, and one time race director, I will try to explain.
The garbage cans are at the end of the table because there is other garbage besides paper cups, usually produced by the volunteers as a product of working the water station.
Ideally, all the paper cups get thrown to the side where all the water drains out, and they get mostly crushed. Then they are swept up and put into big plastic bags.
At this point you have a big plastic bag filled with nothing but soggy paper cups but not a lot of liquid. These don’t weigh much and can be easily recycled. The garbage cans by the table contain all kinds of garbage and cups, and, usually about 10 gallons of water. They are a hassle to deal with. They weigh a ton, and sometimes they split open when you lift them out of the can and make a huge mess.
It is much easier to sweep up the cups and dispose of them conveniently rather than deal with huge bags of liquid. Because of this, we minimize the number of garbage cans and tell people to throw their cups to the side. We would prefer this if everybody did this.
Some people will drink more than one cup. They like to take one cup and drink it at the table and then drink another as they move away. This happens a lot during longer runs. If everybody through their cup away at the table there would be so many that it would create a hazard, so, we have a garbage can at the end for people to throw cups in, and for our garbage, and for a place to put the cups when we do a quick sweep in front of the table during the race.
It would be much more convenient, easy, and make recycling easy if everybody simply carried their cups past the table and through them to the side. We even ask people to do this in the race instructions, but not everybody reads them or remembers.
Vaseline is for chafing. Personally I prefer Bodyglide as it is clean and lasts.
I have probably run 30 or 40 races and I’ll state pretty categorically that the porta potties at races tend to be in better shape than most public restrooms. I can’t recall encountering a single peed on seat. It’s usually pretty heavy traffic and a line, so if you soil the porta potty the next person in line is going to know you did it, and may embarass you.
People tend to be pretty cheerful at these things. Runners and volunteers tend to be pretty nice and polite and friendly.