All managers in Google (engineering and non-engineering) are encouraged to take a 2-day immersive course. There's a course for "experienced manager, but new to Google" and a course for "new manager" with content tailored to the two different populations. There are also many many many mandatory trainings that span the gamut from allyship and inclusiveness, to local laws, to how we do performance reviews and comp. In the first year alone, I would guess something O(~weeks) of these trainings.

There are also countless hours of opt-in training for pretty much any subject where you want to improve your skills.

In Google SRE, combo TLMs are considered to be an acceptable short term solution for team turnover, but not a long term best practice. TLMs are highly encouraged to find a different TL for the team.

In addition, all SRE managers (SRMs) are paired with an experienced manager as their mentor.

Ultimately though, apart from the mandatory trainings, no one can really force you to be a better manager. The big feedback mechanism is that internal mobility is very high, to the point where managers have essentially no power to prevent anyone from leaving their team. So if you suck, you will get bad scores in your own performance review and everyone on your team will just transfer away.

I called out the SRE-specific bits, and a few common practices, but it could be that there are different practices in other engineering orgs.

Source: I'm an SRM, and speak only for myself.

Nobody in tech trains managers. The only difference AFAICT, is that google spreads those underprepared managers across more people. The only place I hear stories of managers with 50 directs is from Google.

That is extremely rare at google these days. The average tech manager has more like 6-8 directs.

Googler here. I'm not sure when you interviewed or your friends worked at Google, but nowadays managers undergo some training (I can't tell you how thorough that is, because I didn't do it yet).

Also, right now, I believe the norm is to have managers and TLs as separate positions, even in small teams (like mine, 5 people in total).

Over half of them worked for Google within the past two years. This is across New York, San Francisco, and Mountain View. One of them said they had a friend that wanted to become a manager and they were made a manager just like that.

This can't be true.

I just went through a 2 day required training as a new manager. This is required training that has to be done within the first 6 months of you becoming a manager.

This has been a requirement for many years.

Source: I'm a googler

Edit: just to add, the same training is required for TLMs. The moment you get a direct report the training becomes mandatory. I suspect there must be some miscommunication from the folks you spoke with.

I think we may have a different definition of "training". A two day training session isn't anywhere near what a manager should be getting. Compare that to software engineering where you will get months of continuous mentorship.