I will add one more category - companies that have or need scale but nowhere near the technical talent that google has. Eg - most telco companies in the US run

I will add one more category - companies that have or need scale but nowhere near the technical talent that google has. Eg - most telco companies in the US run at a scale similar to google. They need most of the software engineering best practices, internal tools teams, etc. They used to have it during Ma Bell times when they had a cash cow. That doesn’t exist and they’re left with scale and the points 1-4 described above. This in general leads them to outsource to lowest bidder contracting firms that compound the shitty software problem. In the end it’s a miracle that all of it works together :)