How to respond to "unfair to write English" comments? I teach mathematics and computing, for example, our department's discrete mathematics course. As is customary for that course, it's used as the first foray into formal mathematics, including a heavy emphasis on reading and writing proofs throughout the semester (required for both our math &amp; computing majors). In response to difficulties I've seen students wrestle with in prior semesters, on the first day of the course I have a slide with this quote:

Writing Proofs in English
“The best notation is no notation; whenever it is possible to avoid
the use of a complicated alphabetic apparatus, avoid it. A good
attitude to the preparation of written mathematical exposition is to
pretend that it is spoken. Pretend that you are explaining the subject
to a friend on a long walk in the woods, with no paper available; fall
back on symbolism only when it is really necessary.” – Paul Halmos,
How to Write Mathematics

Now, the last few semesters I've done this I find that I regularly get pushback on this. For example, this semester I had a student write in the live online chat, something like, &quot;This seems unfair to students who have poor English skills&quot;. And I've been kind of stumped for a short, solid response to that.
Note that I'm at a community college in the U.S., which is part of a large urban university, and about half of our student population is foreign-born. We have a TOEFL requirement for enrollment, but some students indeed have very weak English skills (I've had a small number that apparently needed every course lecture translated by a friend, and couldn't communicate to me directly).
My initial instinct is something like, &quot;You enrolled at a university where the instruction is in English, and has an English requirement for registration, so no one should be surprised at this.&quot; But (a) that seems wordy and byzantine, and (b) misses the underlying problem that people are led to believe that math work is entirely deterministic symbol-pushing, such that some people pursue it precisely because they think they won't need strong language skills (in fact, some of our advisors explicitly say this to students).
Obviously, replace &quot;English&quot; here with &quot;natural language&quot; at whatever institution and location you might consider.
What's the best, shortest response to student criticism that &quot;It's unfair to expect writing in English&quot;?
Related from SE Mathematics: Why there is no sign of logic symbols in mathematical texts?
For writing proofs, full knowledge of English is not necessary. Most proofs can be written using a single tense. It is sufficient (and often advisable) to keep the structure of sentences very simple; that is very similar to how logic statements are written using math notation. Arguably, this exercise requires students to use only a small and simple subset of English level. Most students are expected to have it by the admission requirements of the course they signed on.