In addition to career attractiveness, the thing is tech is an easy target for the modus operandi. Companies in tech deeply need to have a good image and reputation. When your business model is B2C and you're targeting growth at all cost you can't afford a boycott campaign on Twitter, or a few blog posts on medium about sexual harassment, etc.
Other mostly male-dominated industries do not have this characteristic. Do construction companies care about PR? Do financial companies care? Do oil exploitation companies care?
I am not sure Uber users really care about sexism at Uber when it's 2am, they are outside of a bar and need to find a cab. I don't think users will switch away from gmail or google.com en masse because of the male/female ratio in this company. In fact outside of the microcosm of the Silicon Valley and its satellites, I don't think these issues are drawing that much attention.
Other mostly male-dominated industries do not have this characteristic. Do construction companies care about PR? Do financial companies care? Do oil exploitation companies care?