I actually did not know that was a thing, and I’ve been working in startups for over a decade now. I’ve never worked in big tech though, so maybe it’s common there. If a company told me I couldn’t work on side projects without approval, I’d tell them to fuck off.
Sweeping assignment of all copyright—including for things done off-hours—to your employer are common features of employment contracts in the US, which means no open source work without requesting an exception. This is true even in many startups. Absence of that kind of provision is seen as risky by investors or acquiring companies, who fear current or past employees will try to claim parts of the company's IP as their own.
Most are chill about adding exceptions (they don't actually want to claim copyright to that children's book you're writing in your free time) though. Still, sucks and probably ought to be illegal.
I just tell them "this is something I do" and if that's a problem "I'm not giving that up". Leave it to them to end the interview, no need to get an attitude.
I understand the anger from the ancestor post... that this is "standard practice" in the purported "land of the free" is just fucked.
but you do give a classier way to handle it which does leave the off chance that they'd make an 'exception' for some "special" candidate, still I wouldn't like to work in a place like that.
lol I’m not being literal. I couldn’t imagine ever telling an employer literally to fuck off. But I’d decline any job offer that came with that string attached. No amount of money is worth the freedom to do what I want with my own time.