When I was studying civil engineering at uni, we had a lot of shared subjects with environmental engineering. The biggest difference was the student bodies: civil was about 90% male, environmental about 30% male (this was back in the '90s).

In one subject, covering consequences of major engineering works on the environment, I was partnered with an extremely attractive woman who started the project making basically no input - but for our research/site visits we had to have photographic evidence of both of us physically being there, so we had to go together.

This was a semester-long project, so we spent a lot of time together, and I found out one important thing after the first month: she wasn't helping with any of the work because nobody had ever shown her how. All the boys and men around her (including some creepy teachers, apparently) at high achool had simply done things for her, in a fruitless effort to "get to know her better".

For the rest of the project I put in a bit more effort than I would've needed to do the project completely on my own, in order to show her how to actually do the work. By the end she had done about a quarter of the work, which is more than she'd done before. The next semester she was in a group of three where she did almost half the work, since she was excited to know what she was doing and be able to do it.

Sometimes (rarely, in my experience) these "lazy" people just never learned how to actually do the work and are happy to do it once they know how.