Well, it's not exactly the same, is it? Firstly, when straight men make gay jokes at each other, everyone knows it isn't true, it's just a joke. Straight sexual jokes are more likely to have a component of truth to them, which makes them must less pleasant to receive. Jokes between men are part of how men establish pecking orders, but sexual jokes are part of how men signal their attraction to women. Unwanted sexual advances feel unpleasantly intrusive. They're supposed to feel that way. It's a part of human sexuality - we're all strongly motivated to push for our own sexual autonomy.
Secondly, there's the fact that these jokes single her out. She's the only one getting sexual and sexist jokes, so that makes her a special target. If it were all those men making constant gay and sissy jokes to a gay man, you wouldn't think twice about calling it bullying. Hazing becomes bullying if one person gets singled out.
Bullying with a sexual component is straight up sexual harassment. Maybe it isn't meant that way, but that's exactly what it is. A lot of bullying exists because dumb people don't think about what they are doing. "It's just a joke," they say. But it's not. It's the same joke, every day, from everyone. This is exactly the kind of situation where an employer has to step in and tell everyone to grow up and leave it at home. And when I say they have to, I mean it's the law, and they're going to get sued.
Also, the less direct sexism the writer faces show that she is not being treated like the men. The assumption that she is lost or trespassing because she is a lone woman on a building site is pretty sexist. Sure, women working on building sites are rare, but so are women getting lost on building sites. The whole asking if she was "fit" e-mail conversation was cringe inducing - and completely not how a man would be treated.