If he took a whiz on the sidewalk in front of me - probably not. If I were one of the dining patrons in that outside eating area, I hope you would be understanding when I let the father have it. 
VCNJ~
I saw a kid about that age taking a whiz in the shoe department at Wal-Mart once, while his little brother pointed and said, “Ooooo…” The thing that upset me was that his mother was nowhere to be seen, and didn’t turn up until a couple of minutes later.
When I was about that age, I took a crap in a public pool because I was having so much fun I didn’t want to get out of the water. My mom’s boyfriend had to scoop it out with a towel. 
Just to check…
Was the kid peeing into an area where people were eating?
If so, then yes, I would be offended. If it’s illegal to eat there without a shirt or shoes on, I have to assume that peeing in the area is right out.
If not, and you were exaggerating about the possibility of peeing on patrons, then no harm, no foul.
I guess I’m not as nice a person as you, but if I was peed on I sure as hell would have made big deal about it.
As for the rest of the scenario – little kid whipping it out and taking care of business on the ramp – I would not have been offended, since I’d assume he really had to go and when you’re little, when you gotta go, you gotta go. But I wouldn’t have found it funny or cute, either, I’d have found it . . . I don’t know, mildly unfortunate, I guess, in a “poor kid, he needs to work on recognizing when his body tells him to go” sort of way. But again, that’s not uncommon, especially in little boys, who are notorious for ignoring their body’s “I gotta pee” messages unitl the message is MUST PEE NOW!!! So no offense taken – but no gold stars issued either.
We lived in the country, on a gravel road, which also accessed my SIL’s property behind us. She had a home daycare and twice per day, regular as clockwork, a stream of cars would pass down the gravel road dropping off/picking up their kids. When AdoptaSon was 2ish I lost track of him one afternoon. Looked and looked but couldn’t find that little bugger.
I began to hear cars honking their horn and panicked, thinking AdoptaSon was in the road. Turns out he had stripped down to his birthday suit and was standing on our porch railing, peeing and waving to the passing cars, who were honking and waving right back at him
I think I’m being whooshed, but seriously, isn’t five old enough to know you pee in a bathroom? Supposedly he’s toilet trained, and goes to school where he has to follow these rules?
I see a couple of other people noticed it was by a restaurant. Yeah, that would disgust me pretty good. I would not care about the ramp so much but…
You crack me up! I have to face a client whose ad we screwed up this morning, and all I’m gonna’ be able to think about is Ms. Screamy McMortified. (snrk! choke!)
My reaction depends on whose idea it was to pee in public.
I’m not too bothered if a little kid does it, as long as his parents seem to have some grasp of the concept that they should be training him eventually. I’d hate to see harsh words or worse, but some parental blushing and a shrug would be appropriate.
But I’ve seen a parent pull a child over to the wall of my house and instruct the child to pee on my house…in broad daylight…while I was watching…only a few yards from said parent’s OWN house. They were foreign, but really I believe that had little to do with it – foreigners generally know how to operate a nearby toilet, especially one they own.
Can’t say I’m fond of parents teaching kids to urinate on other people’s things in public.
Sailboat
It wouldn’t disgust me, but I’d be annoyed. Its a train station, not a park. I think a five year old is old enough to go look for a tree, if not a toilet. I’ve seen people help their little boys go in public before, but they seem to make an effort to move them out of the flow of foot traffic, so I think thats what the dad should have done.
I don’t have kids, but I do take trains.
If the dad had been too preoccupied to notice what his own kid was doing, or ignored it, I would have been annoyed. But it seems like he took the steps to let his kid know it wasn’t okay, so it’s not a big deal. Kids will be kids, it’s the parents that I’m critical of…