IME both men and women can get away with the level of grooming they choose, until they get to a point in careers where they are trying to break into management or similar levels of 'establishment' careers.
At lower grades, basic adherence to dress codes and cleanliness is fine. Suddenly if you want to be seen as suitable for promotion you need perfectly-fitting suits, recently-cut hair, smart shoes, and attention paid to your face. Which for men means a couple expensive suits, two pairs of shoes to alternate and get 're-heeled regularly and polished, six-weekly haircuts and a bit of moisturiser in the mornings.
For women it's at least all that, but it's a lot harder to find a perfect suit that fits, tops ditto and they don't last nearly as long as men's ones, women's shoes don't last nearly as long, tights are practically disposable compared to socks, and women will be expected to have at least some jewellery and token makeup and most will go for more than a trim at the hairdresser. Given women change size and shape a lot more than men, it's all a lot harder. I really noticed this when going for interviews on maternity leave and having a nightmare just trying to find something presentable to wear, before I could concentrate on the role and plan answers.
It's also an ablism issue - if you can't do up buttons or hold a hairdryer or apply eye makeup, it's very hard to look the part for such jobs.
I think there's ever-increasing pressure on men about looks too - about 5 years after women's pyjamas disappeared to be replaced in shops by bottoms and little sexy T-shirts, the same has now happened to men's, and marketing is trying to pressure them too. The amount of artifice young women apply now has got to a point where fashion has got to swing against it soon, probably helped by economic necessity, just like when hippies, punks and grunge all became fashionable in rejection of the careful gendered styling that was the previous fashion.