Misguided / insufficient language efforts - an observation

This is not really my problem, and I don't think I can do anything about it, but I'd like to share, and maybe it starts an interesting discussion, who knows?

A few years ago, with the help of an association for bilingual families, we met this other German-French family. Their daughter is 10 months older than mine, and the father is the ml speaker (I'm the ml speaker in our family). We meet with them and another bilingual family roughly four times a year, usually around a seasonal German activity like Easter egg colouring or lantern handicrafting, and in summer, for a barbecue. We've been doing this for the last four years, since their girl was a bit over a year old and mine, under a year.

So I've seen this girl grow from a toddler to a 6-year-old, who will start elementary school in September, a year ahead of my girl who is now 5 years old.

During that time, I have (as you know, if you know me from this forum) always spoken our ml with my daughter, who is by now pretty fluent in the ml.

The father of the other girl, however, is not as consistent. If what I see at our get-togethers is his normal behaviour, he speaks mostly ML with her. According to him, he sings her ml bedtime songs and has taught her certain words. At our gatherings, he regularly asks her to say a certain word in ml. For instance, last weekend, they had a birthday present for my daughter. When I reminded her "Hast du merci gesagt?" ("Did you say merci?"), she said "Danke!" and the girl's father said to his daughter "Sag bitteschön" ("Say you're welcome"), which she dutifully repeated.

I've noticed that kind of pattern before, him asking her to say specific words/short phrases in German, often accompanied with "You know how to say that!"

And then later, when she was handing out something and saying "Bitteschön" each time, he asked her to say something else in ml, just as I was thinking "Hey, she's saying that without her dad asking her, he should give her some sort of praise" and then he ignored that and just asked for more. Maybe I'm wrong there, but that's how the situation appeared to me.

Oh, and the father speaks ML even to the other kids, when my daughter and the boy from the third family are perfectly fluent in ml.

I know it's not easy, especially when you're the parent who works long hours and the ML parent doesn't speak ml and you don't have healthy ml grandparents to visit (as we have) or other relatives in the ml country, but I can't help feeling sorry for this missed opportunity, for I'm sure that with consistent input from ml dad, this girl could have at least a passive understanding of ml, and I'm itching to say something about the - to me - misguided efforts of the ml father to get his daughter to "say XXX in ml".

I know there's nothing I can do, but it is so frustrating to see these two girls' language skills develop so completely differently. Or is there?

Sorry, that was a bit long-winded. Thanks for reading if you're still with me at this point. And now to find a title for this thread...