Why technologies and software are never patented?

Google search engine for example is world-changing invention. Why didn't they patent it back in the past and allow competitors like bing, yahoo, etc to come up?

This also applies for youtube and livestreaming service the first time they come out. It was a complete novel idea and I think it's suitable for patent. Why didn't they do it?

I also notice this is almost all app. I've seen some really good apps with novel idea overtaken by copy-cats with bigger budgets.

Most digital-related patents I know are just stuff like logo, names, and other unimportant stuff, I wonder why people don't patent their idea at the first place?