Hairdressers, massage places (the fancy ones (e.g. resort spas) give you an envelope which explains tipping for foreign travelers), sometimes auto mechanics, maître d's (fancy restaurants get expensive when you have to tip the person who sat you, the waiter, the chef, and the sommelier), valets, parking garages where they park your car since it's so tight that all the cars are in a grid (common in e.g. SF), bell persons, hotel rooms (customary to leave some cash on the dresser, again fancier places usually have an envelope explaining it), pit bosses at casinos (you're buying favor), baggage handlers at the airport, gardeners / pool cleaners, repair persons in some cases...

Yeah, it's crazy and dumb and not changing drastically any time soon.

I'm actually having a hard time thinking of any service job in the US where it's not customary (and/or expected) to tip.

Fast food, cafeteria staff, receptionist, fast casual (Chipotle-like places), coffee shop (this is debatable), tech support, cable repair person, salesman, public bus driver, any cashier, bagger, phone support, librarian.

It's so arbitrary though, order a Pepsi from McDonald's no tip, order a Pepsi from a pub, $1 tip minimum. Tip the person who hands you a bottle of beer but not the person who makes your sandwich.

(Self serve soda machines are common now in fast food, but when I worked at McDonald's we poured the soda, no machines, and no tips)

Ok, my imagination clearly failed me on this one!

Though I usually do tip at fast food or fast casual (if there's a tip jar or a spot on the CC receipt), and always tip at a coffee shop.

But the others, yeah... spot on.

The beverage pouring thing is especially insane; I'd never thought about that before. At a bar I'll usually tip 20% for a cocktail, but only 10% or so if I'm poured a beer or soft drink. But even that 10% is crazy when you wouldn't tip a fast-food cashier for pouring you a soda.

"It's so arbitrary though, order a Pepsi from McDonald's no tip, order a Pepsi from a pub, $1 tip minimum. Tip the person who hands you a bottle of beer but not the person who makes your sandwich."

As an outsider, it's all quite insane especially when the baseline isn't 0% but more like 15% for default service in many situations. Or a $1 tip for something ridiculously basic at a bar like getting post-mix soda or uncapping a bottle of beer as you said.

Especially a bodega/deli sandwich maker. Making a sandwich is just as labor intensive as making a cocktail. I load up my sandwiches with at least 10 ingredients (lettuce, tomato, onions, spinach, peppers, banana peppers, olives, salt, pepper, mayo,... Whatever they have!) and the average cocktail has, like, 3-4 ingredients? And it's certainly more labor intensive than carrying a plate.