All three have a strong track record of finding bugs when implemented well. All three also add significant overheads, so there is a cost/benefit ratio to be determined. The relative costs of implementing each strategy will surely vary a lot depending on the nature of any given project. The benefit for any of them would likely be significant for a project that didn't have robust quality controls in place, but you'd get diminishing returns using more than one at once.
I could easily believe that skilled developers had evaluated their options and determined that for their project some other strategy or combination of strategies provided good results without routine use of automated testing and that the additional overhead of adding the automation as well wasn't justified.
You appear to be making your own questionable assumption, which is that the techniques mentioned before necessarily imply a more mature software development process. If a development team didn't use automated testing, I'd certainly be interested to know why, but I can immediately think of multiple plausible alternatives that might have proven to be more effective for that team depending on the circumstances. Unlike the use of brain teasers and popular psychology to assess applicants' value as employees in technical fields, there is a significant body of empirical data to back up the effectiveness of some of those alternative testing strategies.