^- THIS. And to be fair, it's probably nearly always the right decision for a startup that has no idea if it will even be able to put out its first product. Sinking like $300k into an office build-out of any kind before you hire your first key staff would be nuts.
So a startup pretty much automatically is gonna start out looking like what you described in #2. And the inertia keeps them with that setup even after they have the funds to do it right. AND then the big companies wanted to "skin" their environments to look like a startup - so they opt for commercial open office furniture that, while the costs are still dramatically more than the IKEA route, usually offers little actual advantage over the $60 tables and chairs of the real early-stage startup.
If I build a startup that gets to the stage where I'm hiring people, I'm going to consider providing offices (private or shared) for my engineers, as a way to attract talent.
I'm surprised more employers aren't doing this. Yes it costs more but (1) you get a lot more output out of your employees and (2) it helps you hire and retain good employees.
So a startup pretty much automatically is gonna start out looking like what you described in #2. And the inertia keeps them with that setup even after they have the funds to do it right. AND then the big companies wanted to "skin" their environments to look like a startup - so they opt for commercial open office furniture that, while the costs are still dramatically more than the IKEA route, usually offers little actual advantage over the $60 tables and chairs of the real early-stage startup.