My answer is “the Google search appears to be working as designed ”, which is to say it is returning principles … but as @rosie may be getting are they helpful, are they relevant?
That said, the developer principles are also arguably not so great either, except at a very high level. For example, DRY (Don’t Repeat Yourself) … knowing your code ‘should be DRY’, does that principle alone give you techniques to avoid repeating code? Maybe you have to dig a bit deeper to find specific techniques? Perhaps, for example, you would only then know to refactor your code to create a single generic method meaning you can remove several bespoke methods which essentially have repeated code?
So maybe a slightly different question is what principles do, or should, we have in software testing that Google isn’t returning and maybe we can list here?
Personally I like several of the context-driven principles, which Google may not find as easily: http://context-driven-testing.com.
Also, if we think more of principle as a pithy little nugget then some of the chapter titles in James Bach’s Lessons Learned in Software Testing may stimulate further reading/investigation (see the pages in Amazon’s Look Inside tool for all the chapter titles). When I was starting out in testing I’d like to have known a principle like he has in a chapter title: “you will discover things which will ‘bug’ someone whose opinion matters”. Cute !