At Google these trainings are almost exclusively for managers. They used to have a quarterly class for non-managers but it was always oversubscribed.
Managers have a network: lots of manager-focused meetings, trainings, perf rating calibration sessions, etc. Even if they don't work on the same projects they'll have much more interaction than ICs and TLs have which each other. ICs and TLs who work on different projects have to seek each other out, and there's no official forum for this.
leading without authority is literally a course on Google's internal training site. You can just sign up for it. I did. It was good. Later I lead a session on it, which was also fun.
The resources are certainly there at Google, but you do have to dig them up yourself. If you're a manager you're required to do them.
You've ironically proved my point - there may be resources like this, but they require much more effort to access. Furthermore, like of a mandate means that those who aren't required to take the class may not even be aware that it exists.
If you're a manager who hasn't taken Managing Within the Law or whatever, you may get in trouble, but as an IC you don't even get the option!
I don't see how this proves your point. It's like saying there is no way to get an education because no one forced you to go to university.
You can go on grow and search for "classes on leadership" or whatever else you're looking for and it will appear. It's not like you have to guess the title ahead of time. Grow is quite literally a course catalog.
Well I'll be sure to get promoted twice in order to qualify! At that level they're probably paying you upwards of $1M/year, so they'd better support you
Managers have a network: lots of manager-focused meetings, trainings, perf rating calibration sessions, etc. Even if they don't work on the same projects they'll have much more interaction than ICs and TLs have which each other. ICs and TLs who work on different projects have to seek each other out, and there's no official forum for this.