[tuxracer]

That's very true Google has never been as disciplined when it comes to design guidelines. But aside from purity to specific guidelines there is a lot of data that show hamburger menus are death for discoverability of whatever is tucked away in them. Google has been slowly moving away from that direction for years first with the removal of the hardware menu button. As far as tabs go, having tabs, and on the bottom, is tremendously helpful especially on larger screen devices. All things Apple has likely known all along and hence their original design guidelines that Google seems to be adopting more and more of over time.