The why is a much harder question.
You're right about it probably being true, this is not the first study to find something similar, there's two others reported on here: Patients have better outcomes with female surgeons, studies find
It's interesting that this study looked at the proportion of women on the surgical team (not the composition of the surgical team for any specific operation):
Overall, female surgeons performed 47,874 (6.7%) of the operations. Female anaesthesiologists treated patients in 192,144 (27%) of operations.
Hospitals with teams comprising more than 35% female surgeons and anaesthesiologists had better postoperative outcomes, the study found. Operations in such hospitals were associated with a 3% reduction in the odds of 90-day postoperative major morbidity in patients.
There's some speculation in that first link about differences in aggression and risk-taking. But, given the relative rarity of female surgeons, it could just be a competency effect. If women are a small minority for reasons not related to competency, and 93.3% of surgeons are men, it suggests that almost half the men are in the job because a more competent women didn't get it. Groups with more women do better simply because they didn't discount half the talent pool quite so heavily.
Obviously, people want that (the actual question asked was about an "urgent" need to see a doctor).
But this proposal is just a repeat of one of Blair's worst policy failures, without acknowledging how or why it failed.
When New Labour introduced the 48 hour target to see a GP, the vast majority of GPs 'met' the target by closing down their phonelines as soon as they ran out of appointments. In the process, they turned the 48 hour target into a 24 hour target because otherwise they'd only have been able to open the phoneline every other day.
It was very bad back then. It's much worse now because the NHS was at least relatively well-funded under Blair.
Not that they're announcing this because they think the policy will work, obv. Just doing their best to make sure the voters blame everyone but them.
[The link is to a video of an election Question Time audience haranguing Blair about the foolishness of this target.]