They make the official policy in-office to set the expectation that that's where you'll be, and then they can negotiate exceptions on a case-by-case basis. I've never seen a high-performing Googler (meaning one who has successfully launched a project) turned down for remote work or office transfers. They don't want the non-performing Googlers (who possibly might outnumber the high-performing ones) working remote though. If you're meeting with engineers as an external partner or customer, it's almost certain those are high-performing engineers, because they wouldn't be put in that position otherwise.

Why not?

In most knowledge work - not just Google - you're fine as long as you're either putting in effort or getting results. After all, software development has plenty of risks, it's possible to fail to deliver for many reasons other than being lazy. But when you are neither putting in effort nor getting results, that's when you're at risk of getting fired, because the company starts to wonder why they're paying you. Remote work makes it much harder to observe the "putting in effort" piece.

I don’t get it. There’s code and working features. That’s the result.

It's not just about the code, it's also about the culture.

Non-performing staff could be non-performing for different reasons - not just output - and it's often easier to spot those reasons (and address them) when you're working in the same office.

Source: I've been running a company with hybrid in-office + remote staff for 15 years. Would be happy to expand on the above if asked.

They don't want to increase the performance of the low-performers?

When Google got big, it got stupid.

I don't think I've ever had a manager that could be convinced to care about this even if some level of management did in fact care. Who the hell wants to spend time taking attendance like a schoolteacher?