It was not always like this. Google was very secretive in the early days. We did not start to see things until the GFS, BigTable and Borg (or Chubby) papers in 2006 timeframe.
Google publishes detailed papers of its architecture once it’s built the next version.
AI is a bit different.
Page Rank
By 2006, Google was 8 years old. OpenAI is now 10.