I know you didn't ask which countries don't have that tradition but I can confirm that in Japan, infants are taught precisely the same stroke order and construction as adults are expected to use and they read the same typefaces.
@Mark Simonson There's no technical reason the style of emojis couldn't be matched to a typeface. Matching symbols to typefaces is already done on a smaller scale with characters like hearts and fleurons. Imagine you were tasked with designing hearts and fleurons for Sabon, Didot, Futura and Franklin Gothic. You'd design them in a way that stylistically harmonizes with each typeface. Then, the client requests 3 more symbols: an apple, a happy face and a birthday cake. Next, they request colors, only for the hearts and fleurons. You'd create palettes that suit each typeface and determine what kind of gradients are needed, if any. Now they want colors for the other symbols. I'm sure some designers would bail out on such a project but if you can get that far, the rest is a matter of scale. At that point, your sample characters could be handed over to a competent art department who could fill out the rest of the emoji set in the same style.
Emojis are crude tools because there are no emoji choices for designers. Picture a banal, fully-saturated-green cartoon leaf with airbrush shading and expressionless black outlines. What if that was the fleuron included with every font in existence? Gross, right? Well that's emoji in 2018. The same emoji glyphs are used for children, adults, serious themes and silly themes. They're accompanied by arbitrary typefaces in styles determined by phone manufacturers. We've yet to see a tasteful application of emoji but I think the potential is there.
Maybe emoji is a fad but nobody knows. We're at such a rudimentary stage that it's impossible to determine that. It's all down to the younger generation. They'll determine whether or not they're still around in a century.