I agree with dannyb re. the work - cold-calling is still hard selling even when you're calling 'cool and funky' people. I worked for a high street agency years ago, and then, as I believenow, Robert Walters was seen as upmarket, although they often poached consultants from us and we shared the same candidates. I think they were seen as exclusive beacause they didn't have loads of offices everywhere.
The reason your dd is not getting interviews with prospective employers is this: employers can fill graduate trainee posts through the milkrounds and such, so they don't need to go to agencies and incur a fee. I'm sure it is still extremely rare for an agency to place a graduate in a trainee role, and I'm surprised no one has explained that to her.
We used to place students as temps in the summer holidays, and sometimes graduates would do this just to be working, but a fresh graduate is not a prime candidate in the perms market.
Having said that, consultants can always spot a potential consltant (and they probably get a little bonus for placing her), so she probably will do well. It is really hard work, though, and you're constantly monitored and judged for your 'figures', which obviously would not suit some people.
Re. going back to work after babies: I'm not convinced it's easy to go back to - maybe in a training role, but it's so cutthroat and youth-oriented I can't see how anyone could manage it. Sorry this is long - hope it helps.