[wyaeld]

The OP is incorrect, most of the large organisations he cites do not practice trunk-based development.

Google has a monorepo and what could describe as 'submit patch for code review'. Only certain engineers can approve reviews and trigger the patch being applied to the trunk.

https://github.com/google/eng-practices

Many of the others also have variations, but unlikely that any organisation with 1000+ engineers has a monorepo with all of those engineers directly committing to it.