Under what circumstance does using 普通形 of a verb imply a request?

Question

Couple of days back, I was at Japanese class and 先生 wanted us to return the printouts he handed us earlier. 先生 used the sentence 「プリントを出します」instead of 「プリントを出して」. Some other examples I have seen are:

1. 関係者は出社したことを確認します - Related party, please confirm attendance
   
2. 出社したら、自分で「出社しました！」メールを送る - When you arrive, send a mail stating you have arrived
   

These examples are requests to other parties to do something. From what I understand, to make requests, one should use the て- form of verbs. The example sentences uses the ます/る form in making requests. Is this even possible? If I am not mistaken, using the ます/る forms of verbs implies (first person) will do (verb), for example: リンゴを食べます means (I) will eat the apple, and not please eat the apple. And if it possible to use ます/る to make requests, how can I differentiate (other then by context) whether it is a request or whether it is what someone will doて

Answer 1

Dictionary-form and masu-form are common in product documentations and how-to type sentences (e.g., 扉を開けるにはこのボタンを押す/押します), which explains why 出社したらメールを送る is fine. But it doesn't work as an immediate request/order. Ordinary Japanese speakers don't say プリントを出します in the context in question.

Is this 先生 a professional Japanese teacher who teaches both beginners and advanced learners? I have heard that at the initial stage of teaching Japanese, student do not even know imperative forms, so it's common for a teacher to say 教科書を開きます to beginners when 教科書を開いてください is normally appropriate.

Sometimes plain dictionary form is used to make a quick and strong order (e.g., 立つ! ～しない!), but this doesn't apply for masu-form. See: Plain form as imperative

Also note that te-form as a request sounds fairly colloquial. If your teacher generally uses ます/です during lessons, プリントを出して would sound out of place.