This is probably because Silicon valley companies have tech cofounders and first early hires are also engineers who become involved in important decision making

This is probably because Silicon valley companies have tech cofounders and first early hires are also engineers who become involved in important decision making beyond engineering, like product and even strategy. This creates a culture of empowering engineers. On the contrary, companies where tech is an afterthought-- well why would you empower your engineers to make business critical decisions if you're running a hospital or a sports team.