I think it is like when people say an old horse is thin because they're old. They don't have to be. Same with a mare that's nursing.
I asked someone that I know well "If they were a complete strangers horses, and you drove by and saw that, what would you think?" They admitted that because they've known the owner for nearly 15 years, that they just assume that it's all okay, if had been a strangers place they would probably be horrified.
All the pictures that everyone put, thanks, it puts in perspective that yes it's okay to lose conditioning, to become a little ribby, but with a good diet that doesn't have to become a big problem. That there is no good reason for the mares to be in that condition, it sucks that nothing will be done, nothing can be done, but the mares should be grazing soon hopefully it will help some too.