Looked these up myself, and, as I suspected, all of them are made of rayon, which is basically bootleg cotton/silk/wool/whatever natural fiber you want to mimick. Really popular in cheap clothing these days. Becomes weak in water and has very poor elastic recovery. Also very prone to shrinkage.
The care directions on Torrid's site say "wash cold, hang dry," though normally dry cleaning is what's recommended.
So with as lazy as I imagine she is about clothing, even if she had no problem getting into these dresses, they're still likely to fall apart after a few uses.