Considering the massive over supply of labor, I’d say they could very easily replace that 20% several times over before they had any problems finding more engineers.
Techies work in a seller's market (as evidenced by the comparatively huge salaries they command). There is definitely no "over supply of labor".
One of Google's biggest assets is their huge army of talented techies. I'd go so far as to say losing that would be an existential threat to the business.
Comparative to what? Big tech companies are wildly profitable for their owners.
Techies make a lot of money compared to other professions because we genuinely produce a disproportionate amount of value, but that doesn't imply we're in a seller's market.
One way you can tell that there's no dearth of labor is that most companies round an "unsure" in the interview process to "no," not "yes."
I sugggest you ask a non-tech friend about their experience getting a new job: how many applications they've sent out, how many responses they've received and how many interviews they've actually been to. Then compare that to a software dev's hit rates.
I submit to you that a halfway decent software dev will have a hard time being unemployed: they might not get hired by FAANG and they might have to code in $LANGUAGE_I_HATE, but they'll be able to get a job at a reasonable salary.
Also, consider the fact that there's been a large number of businesses focused on recruitment specifically in the tech area. That's because everyone wants to hire devs and they're willing to pay recruiters to channel the funnel their way.
A large part of supply and demand is the amount of immediate liquidity. Employers seem to have the upper hand when hiring typically because they have a bunch of options right then whereas few applicants have multiple simultaneous offers and if they do, they don't have many. But that's not the same as supply and demand of labor on a longer timescale.
Somebody who's thought more and more clearly about this could write something better about it, but I felt like pointing out what I think is overlooked.
The issue isn't finding more engineers, the issue would be the sudden loss of institutional knowledge, the paralysis while trying to maintain basic functionality, and the distinct possibility of critical, catastrophic failure due to broken processes from missing people. What's the chances that the 20% of employees who don't show up include everyone needed to prevent a failure of Google's entire Ads product?
When say, the teachers go on strike in Chicago, it's not that it's impossible to hire new teachers, it's that someone in the meantime of negotiation has to watch over (and ideally educate) all of the kids that those teachers are responsible for teaching.
Wherever you work, try to imagine a random 1 out of every 5 employees missing one day. How likely are you (and everyone else still there) likely to run into problems conducting your general work. And imagine that that is going to continue until your company manages to interview, vet, hire, onboard, and train all of those people back.
...Or, the corporation could just capitulate to demands. Collective action is incredibly powerful.
This sounds like an Econ 101 understanding of the labor market.
Most (white collar) employees are not as fungible as people assume, first of all. Two "Senior Back-end Developers" might have such different work experience that one would ramp up on a project in 5 days, and the other would take a couple of weeks.
Second, all turnover is expensive. For a large company like Google, turnover of 100 people could easily cost millions.
Unfortunately, unless those people worked on ads, Google's investors (and therefore C-suite) probably wouldn't miss them much.
