The "hansom" phrase is used almost exclusively on non-adult males because once boys hit 18-20 what we hear all the time is "Smile so the customers will think you enjoy working here" or "Smile so the customers will think you're friendly -- that way they'll relax and be easier to sell stuff to" or "Smile so people will think you're friendly. No one wants to make friends with a stranger who looks like they're mad" or "You need to smile more, dude. It's a chick magnet" or "Smile because it makes you look more powerful and self confident."
If you think about it, all of those phrases are to some extent conveying the idea that smiling makes you look more attractive so you can acquire customers, friends, females, gullible muppets, or whatever and manipulate them for your own benefit.
In essence "You'd be prettier if you smiled more" is exactly the same advice: "Make the package more attractive so people will want to be your friend and buy what whatever product, idea, philosophy, or thing you're selling."
All boys and men in customer-facing sales or service occupations or occupations that involve persuasion in some other way do have to always look friendly and helpful. And so does any guy who wants to attract nice girls or good friends. Pat Boone said so! https://www.amazon.com/Twixt-Twelve-.../dp/0139349928
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