I know what you mean op and yanbu.
I have two ends of the spectrum (although my mum isn’t as ott as yours).
If my mum has my youngest and I text to ask how he is she’ll reply with ‘he’s having a great time! Been good as gold and has just eaten his body weight in pasta! Him and ds1 are playing blocks, it’s so sweet!’ (Or similar). She knows that if anything is wrong with the dc she needs to call me (in the middle of the night or whatever) and has once before...knowing she will makes no contact from her ok and comforting iyswim?
MIL on the other hand shoos me away and almost point blank refuses to answer questions (general, rare ‘how’s everything?’ questions). She’ll say ‘fine! I have done this before you know!’ or ‘he’s ok...now leave the kids to me, don’t worry’.
She’s also said before she’d only call if one of the dc got sick if they needed A&E or something. It was impossible to explain that she needed to call us, as parents, before it progressed and we needed to be sure of that before feeling comfortable in leaving them.
It makes me very uncomfortable and as a result I rarely leave the dc with her (she asks btw, I’m not dumping you them there) and would choose other options first if I could.
I don’t think it’s unreasonable or controlling to want to have an open dialogue about the wellbeing of your child with the person caring for them.