All of your examples showcase the fun part of a job with public interaction. What happens when you need to be the mouthpiece of your store's rules and policies, telling someone they are not allowed to return an item, or negotiate a lower price, or have a similar request? Whatever your personal opinion of the merits of their argument, you may not have the authority to deviate from the policy, and must expend emotional energy trying to get the customer to acquiesce without causing a scene.
Yeah, there are rules that I can't spontaneously break, BUT I wouldn't say that makes this statement true: "we find there is no depth to their friendliness, nor is there any spontaneity." Maybe I'm just lucky, but I find I have a lot of flexibility in exception management, so it's rare that I have to really put my foot down on something. But even when I do, I don't see what the big deal is.
I mean, just being a regular person interacting with people in a non-professional capacity, there are certain things I won't spontaneously allow. If someone started spitting chewing tobacco on the floor of my kitchen, I wouldn't be particularly flexible either. In a workplace setting, sure, there are probably more rules, and it's not always up to my better judgement to break them (some people will try to return items we don't even carry for a full-cash refund with no receipt), but I don't see how this makes my interaction with them essentially meaningless, as Mole has said.
I agree that having to enforce rules/policies that displease customers (and maybe even displease me), is very draining, but that wasn't what I was disputing. And even then, I maintain that sometimes there are spontaneous ways to defuse tension in those situations. You don't have to fall back on the company script.
For example, a lot of people hate giving me their personal information when they return something (I need their name, address, and phone number), and I can sense their impatience and irritation as I ask: name? Oh, how do you spell that? address? city? postal code? phone number? So then I usually make a dumb little joke after it's done like: Thank you for playing the Big Brother quiz bowl, here's what you've won! And then I give them their money back. Somehow, stuff like that makes most people laugh.
Or sometimes I have to harass everyone who comes into the store about a deal we have on, so then I try to have fun with it. It's kind of hard to explain in words (I think my tone is very important), but a lot of my interactions look like this:
Me: Good day, I trust you two are in high-spirits today?
Customers: Uh...yes?
Me: Excellent, then my trust is well-founded! Oh, just one thing before I let you go and enjoy your life. We have a deal on. You might want to sit down for this.
Customers: Hm?
Me: You see those books over there.
Customers: Yeah.
Me: Well the more of them you buy, the bigger the discount you'll get. If you buy 2, they're 20% off. If you buy 3, they're 30% off. If you buy 4, they're 40% off! If you buy 10...unfortunately they're not free. So don't try and get smart with me! The cap is 50% off.
Customer A: You can't trust Gertie here, she's always trying to pull a fast one.
Me: Oh I can tell, she has a mischievous gleam in her eye. I've got my eye on you, Gertie.
Customers: *they chuckle, with any luck*
Although some customers, that kind of approach just won't work. Sometimes I just get out as quick as possible, sometimes I emphasize different things. I have a lot of variations depending on my read of the person and depending how they reply each step of the way. The whole process happens very fast, so I'm not sure how it works exactly.