There's an attitude I've noticed also of, "we're not Xyz." Hate to break it, but most problems aren't really that unique. If you resist learning the lessons from other companies, you will repeat their mistakes.
As is often the case...
Very often the first generation of employees at a startup will consist mostly or solely of folks with 0-3 years experience at most. Then if that startup survives, all these people are "naturally" promoted to senior / team lead / tech lead levels...
> It can be very frustrating being someone with experience that has to sit back and watch big mistakes be made despite warnings from people who have done it before.
I feel you, brother. I've been there too.
> There's an attitude I've noticed also of, "we're not Xyz."
It's called "young arrogance".
"Hey, we're a bunch of straight-out-of-school engineers, but clearly we can do better than Google because we're awesome!".
In reality, many if not most startups are run by inexperienced and often immature managers and engineers who are substantially less qualified and skilled at running a team than their equivalents in more mature tech companies.