I found a moving interview with Hilla Becher, which, unfortunately, only appears to be available in German. I translated some of the passages that struck me below.

Q: You spent your life photographing industrial memorials: Hundreds of furnaces, hundreds of water towers, hundreds of coal bunkers. Is this about being complete?

A: At the end of his life, Bernd often said: Hilla, we haven’t finished the job. And then we almost started fighting because I said: What do you think? We can’t finish our job, since it’s infinite.

Q: Was it difficult for him to accept this?

A: I think it was. He never managed to tell me what he meant by “finished”. We knew we would not be able to photograph everything. In Russia, for example, it turned out to be too difficult, we did not manage to get permission to work there.

Q: Were there family photos at the Becher’s house, for example at Christmas?

A: That didn’t exist with Bernd, but I always had a small camera on me. It was important for me, to keep memories.

Q: Who did you take pictures of?

A: Our son, my mother, just family. Doing group portraits was my favourite thing to do. But I did not just shoot left and right but arranged everybody: the first row sitting down, the second row standing, the third row [standing] on a table. Very conventional.

Q: Why was your husband not interested in such photos?

A: He rejected them because he was not interested in taking them. Actually, he was never interested in photography.

Q: That is an unusual statement about a man who spent his whole life on it.

A: Originally, Bernd did sketches. In the beginning, he sketched industrial landscapes. But he never managed to finish his work, because he was so precise. Often the object was demolished right in front of his eyes […] The demolishing, the decay happened faster than he could sketch it.

Q: So then he took photos?

A: Right. He borrowed a 35mm camera and took photos, to use them for his sketches. That’s how it started, photography as the means to an end.

[…]

Q: Did you sometimes go on vacation together?

A: A real vacation, two or three weeks, that we never had. Bernd was not interested in that at all. I am currently trying to make up for it. My son is helping me. Just a little while ago we went to Cuba together.