Mainly I’m asking all of you why do people insist on only answering 1 question out of an e-mail where there are multiple?

They are either distracted or don’t understand that there are multiple questions. In a few cases they don’t want or know how to respond to multiple questions in an email format because they are afraid of changing your text formatting (yes, at least three people have told me that was why they didn’t).

Do people just not read?

Quite a few have terrible reading comprehension.

Are people that lazy?

Some are.

What is going on?

It is a mix of a lot of things, all of which are different versions of poor communication skills.