The fact that this is common means nothing - what kind of argument is that... law breaking and human exploitation is also fairly common - does that mean it OK to do it?
> "Must be willing to work extended hours and weekends as needed".
I also had some emergency situations where I had to fix something or help someone - and it is normal for me - but I can count that using fingers of one hand during a year.
What is NOT normal and should instantly raise red lights is that this is part of job description. Stop pretending it OK to do this in a company that is managed properly it should not take place.
There is a lot of room between "it's okay" and "it's slavery".
In this case, if "as needed" means "during the occasional launches of our experimental rockets, because launch windows happen at sometimes awkward times", it's quite a bit more understandable than "pretty much every deliverable, because we poorly set arbitrary deadlines."
Your initial point was good - it does not happen at "pretty much every" software company. I am not sure it's a red flag here, depending on the actual intent.
Sure, the only problem I see here than some people that work on startups think it's OK to force people to work overtime all the time - and for them it's the norm - where it should be an exception.
I saw it multiple times it even sometimes ends up with lawsuits like @ LinkedIn. I truly believe people can succeed without creating this kind of bad work culture.
> "Must be willing to work extended hours and weekends as needed". I also had some emergency situations where I had to fix something or help someone - and it is normal for me - but I can count that using fingers of one hand during a year.
What is NOT normal and should instantly raise red lights is that this is part of job description. Stop pretending it OK to do this in a company that is managed properly it should not take place.