Sister in law

Why does my SIL ( brother’s wife) feel entitle to do their baby’s laundry at my house?? Her baby is 1 month old and they’ve been doing her laundry here before she was born because they think public laundromat has a lot of germs 🙄🙄🙄. Like my machines don’t have germs 🙄. I think this is a little bit too much now, I thought they were going to do laundry here just once. My husband & I don’t want to say anything to them because we don’t want to be rude but we think it’s enough already and his sisters have never come here to do their laundry.