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I'm pretty sure that's not the case, i.e. it's not the lack of technical knowledge of being able to tell which one is faster. Rather, it's probably a cultural thing. Nowadays, it's pretty fashionable to write web apps (and more) in dynamic languages, because the industry promotes the fast and loose way of doing things in general. JavaScript, microservices, Agile™, fast prototyping (that inevitably ends up in production), you name it – it's all good intentions, often going haywire.
(And in the workplace, there's the "it's so much easier and faster to write" hammer too, which appeals to higher management so much. But then again, higher management aren't the ones to debug the fast-to-write code after the damage has been done )
The rising popularity of IT and programming as a prospective career path also plays an important role in this change. It's easier to teach newcomers using dynamic scripting languages – they don't need to know what a compiler is or why they would need one, they don't need to learn about formal types, only some very basic, unwritten intuition thereof, and they don't need to be introduced to the concept of functions on day 0.
It's a shame, however, that so many courses, programmes, universities, freelancer teachers, etc. in this field don't offer or emphasize follow-up material, with which people could learn at least one statically-typed language. As a part of my doctoral studies, I am required to teach undergrad and graduate courses as well, and my fellow PhD students and I equally feel that such knowledge about basic computer architecture, systems programming, and a formal notion of types is sorely missing from curricula at universities and elsewhere.
(Then, of course, there are the universities at the other extreme, those who mistake IT for pure mathematics, and teach nothing but discrete math and type theory for 6 semesters. That ain't doing any good, either.)
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