Why MIT switched from Scheme to Python (2009)

Isn't this just part of the broader trend of CS departments switching away from teaching computer science to teaching computer engineering, which in turn is part of the more general trend of colleges becoming more vocational?

LISP dialects like Scheme are excellent for teaching pure computer science because they are the closest thing to executing lambda calculus expressions. Whereas Python is excellent for teaching applied computer engineering, because it's essentially executable pseudocode for imperative languages, and imperative languages are the most common language a computer engineer encounters in the real world.

Yes. One of the biggest complaints that computer science departments used to get from students is that they weren't learning any languages that employers are using.

There were plenty of less rarefied CS departments that were concerned about this, and they taught C, C++, or Java in their introductory classes.

Ultimately, it doesn't matter. It's your first language, not your last.

How many people do you know who are monolingual?

Human languages and programming languages are not comparable. You will need a lot more effort to become fluent in a second human language than in second programming language. Even if the human language is Esperanto (designed to be really easy for speakers of European languages), and the programming language is C++ (perhaps the most inconsistencies and foot guns) the programming language will need a lot less effort to learn to a high level.

They're not directly comparable because humans have an inbuilt ability to learn human languages.

The vast majority of people on the planet know more than one human language and know zero computer languages. It's literally the opposite of what you're claiming.